as requested: CPU/MB/Mem/Video
this is all in the assumption you aren't terribly adverse of a little overclocking btw. there is no reason whatsoever not to overclock a C2D at least lightly.
so lets start off with the CPU
Intel Core 2 Duo E6750 Conroe 2.66GHz 4M shared L2 Cache LGA 775 Processor - Retail $225.00
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115029
or
Intel Core 2 Duo E6850 Conroe 3.0GHz 4M shared L2 Cache LGA 775 Processor - Retail $345.00
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115028
your choice really. i'd go with the first & overclock it for value. the second can be overclocked as well obviously, but in my opinion it isn't worth the extra $120.
further there are Quad cores
Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache LGA 775 Processor - OEM
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115017R
they say Crysis will be able to take advantage of it, but atm no game nor program takes any advantage of it and it clocks far lower and overclocks worse than any C2Ds. i dont think i'd bother with that yet.
motherboard
ASUS P5K3 DELUXE/WIFI-AP LGA 775 Intel P35 ATX Intel Motherboard $246.99 or if you take the OEM $227.72
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131181
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131181R
it is to be noted, that with this kind of mobo, the mobo itself benefits from a cooler blowing down, and not sideways (like for instance a towercooler or a zalman 9500. these coolers are extremely good, i own one myself, but the motherboard is slightly hotter that way.)
overall a very good gaming motherboard and good overclocker to boot, but has no SLI. it has crossfire, but still. it is up to you to figure out in the future if there is a chance to put SLI or crossfire. i always thought it possible to get an extra card 'later', but in reality i likely will never put in SLI or crossfire myself. i'll go on from the assumption you dont care about SLI/crossfire.
HOWEVER! this type of motherboard requires DDR3, which is more expensive atm.
if you want to use the much cheaper DDR2 listed further down, you'll need to get a motherboard that supports DDR2. like a ASUS P5N32-E version with 1333fsb support!
as for the gfx, remember: NONE HAS PROVEN THEIR DX10 WORTH!
Leadtek PX8800 GTS TDH 320MB Extreme $294.99
http://www.newegg.com/Product/Product.aspx?Item=N82E16814122022
pretty good bang for buck gfx card. however, with the budget you gave me, we got plenty $$ to spare. either way, the card listed above is the 'prudent' choice, as none of these cards have ever been tested in dx10.
if you're feeling a lil' nutty, you can get an 8800Ultra and still be in budget. (but be SURE to have a PSU that can haul that mastodont and a case that can house it)
MSI NX8800Ultra-T2D768E-HD-OC GeForce 8800Ultra 768MB 384-bit GDDR3 PCI Express x16 HDCP Video Card - Retail $614
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127288
or if you're feeling slightly more moderated:
EVGA 768-P2-N831-AR GeForce 8800GTX 768MB 384-bit GDDR3 PCI Express x16 HDCP Video Card - Retail $546.99, but only $486.99 after full rebates etc)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130072
the memory... fuck! harder choice than expected. i don't really see why to buy expensive DDR3 memory yet, as the latencies are too high atm and DDR2 is becoming dirtcheap (especially with the Mail-In rebates thing on newegg). amongst the best value are these:
(please note that the listed memory sticks are quite high, so watch out when buying custom CPU coolers, it might interfere.)
OCZ Reaper HPC Edition 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory - Retail $180.99 (only $140.99 after Mail-In rebates!)
this memory is the best bang for buck, guaranteed. also overclocks nicely, but has trouble if trying to lower latencies (so overclock the fsb, without lowering latencies).
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227191
CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory - Retail $230 ($200 after rebates)
http://www.newegg.com/Product/Product.aspx?Item=N82E16820145173
OCZ Reaper HPC Edition 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 1150 (PC2 9200) Dual Channel Kit Desktop Memory - Retail $220
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227196
that's about it. do note that this is not an end all be all rig or whatever. it is what appears to me to be good bang for buck with reliable hardware. truly digging to find the best of the best would require hours if not days. as such, my words are advice and not gospel.
and as such, my advice holds no legal ground for you to sue my pants off if it blows up in your face.
this is all in the assumption you aren't terribly adverse of a little overclocking btw. there is no reason whatsoever not to overclock a C2D at least lightly.
so lets start off with the CPU
Intel Core 2 Duo E6750 Conroe 2.66GHz 4M shared L2 Cache LGA 775 Processor - Retail $225.00
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115029
or
Intel Core 2 Duo E6850 Conroe 3.0GHz 4M shared L2 Cache LGA 775 Processor - Retail $345.00
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115028
your choice really. i'd go with the first & overclock it for value. the second can be overclocked as well obviously, but in my opinion it isn't worth the extra $120.
further there are Quad cores
Intel Core 2 Quad Q6600 Kentsfield 2.4GHz 2 x 4MB L2 Cache LGA 775 Processor - OEM
http://www.newegg.com/Product/Product.aspx?Item=N82E16819115017R
they say Crysis will be able to take advantage of it, but atm no game nor program takes any advantage of it and it clocks far lower and overclocks worse than any C2Ds. i dont think i'd bother with that yet.
motherboard
ASUS P5K3 DELUXE/WIFI-AP LGA 775 Intel P35 ATX Intel Motherboard $246.99 or if you take the OEM $227.72
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131181
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131181R
it is to be noted, that with this kind of mobo, the mobo itself benefits from a cooler blowing down, and not sideways (like for instance a towercooler or a zalman 9500. these coolers are extremely good, i own one myself, but the motherboard is slightly hotter that way.)
overall a very good gaming motherboard and good overclocker to boot, but has no SLI. it has crossfire, but still. it is up to you to figure out in the future if there is a chance to put SLI or crossfire. i always thought it possible to get an extra card 'later', but in reality i likely will never put in SLI or crossfire myself. i'll go on from the assumption you dont care about SLI/crossfire.
HOWEVER! this type of motherboard requires DDR3, which is more expensive atm.
if you want to use the much cheaper DDR2 listed further down, you'll need to get a motherboard that supports DDR2. like a ASUS P5N32-E version with 1333fsb support!
as for the gfx, remember: NONE HAS PROVEN THEIR DX10 WORTH!
Leadtek PX8800 GTS TDH 320MB Extreme $294.99
http://www.newegg.com/Product/Product.aspx?Item=N82E16814122022
pretty good bang for buck gfx card. however, with the budget you gave me, we got plenty $$ to spare. either way, the card listed above is the 'prudent' choice, as none of these cards have ever been tested in dx10.
if you're feeling a lil' nutty, you can get an 8800Ultra and still be in budget. (but be SURE to have a PSU that can haul that mastodont and a case that can house it)
MSI NX8800Ultra-T2D768E-HD-OC GeForce 8800Ultra 768MB 384-bit GDDR3 PCI Express x16 HDCP Video Card - Retail $614
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127288
or if you're feeling slightly more moderated:
EVGA 768-P2-N831-AR GeForce 8800GTX 768MB 384-bit GDDR3 PCI Express x16 HDCP Video Card - Retail $546.99, but only $486.99 after full rebates etc)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814130072
the memory... fuck! harder choice than expected. i don't really see why to buy expensive DDR3 memory yet, as the latencies are too high atm and DDR2 is becoming dirtcheap (especially with the Mail-In rebates thing on newegg). amongst the best value are these:
(please note that the listed memory sticks are quite high, so watch out when buying custom CPU coolers, it might interfere.)
OCZ Reaper HPC Edition 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory - Retail $180.99 (only $140.99 after Mail-In rebates!)
this memory is the best bang for buck, guaranteed. also overclocks nicely, but has trouble if trying to lower latencies (so overclock the fsb, without lowering latencies).
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227191
CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 1066 (PC2 8500) Dual Channel Kit Desktop Memory - Retail $230 ($200 after rebates)
http://www.newegg.com/Product/Product.aspx?Item=N82E16820145173
OCZ Reaper HPC Edition 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 1150 (PC2 9200) Dual Channel Kit Desktop Memory - Retail $220
http://www.newegg.com/Product/Product.aspx?Item=N82E16820227196
that's about it. do note that this is not an end all be all rig or whatever. it is what appears to me to be good bang for buck with reliable hardware. truly digging to find the best of the best would require hours if not days. as such, my words are advice and not gospel.
and as such, my advice holds no legal ground for you to sue my pants off if it blows up in your face.