i would have to say that to be honest, the less advertising there is for a game, the higher the chance ill buy it.
the higher the opinion of the people here of a game, the higher chance ill buy it.
no advertising purchases where here didnt influence:
NWN2 = 8
NWN = 9
M&M

M (ugh) = 3
Fate (kid version of diablo) = 7
Fable = 9
Oblivion = 3
Gears of War = 5
Orange Box = 9.5
Dragonshards = 8
Halo = 6
Sacred + exp = 8
black and white 2 = 6
Age of Empires 3 = 7
Battle for Middle Earth 2+exp = 9
Games i bought based on info here:
*Stalker = 7
*Supreme Commander = 8
*Gothic 2 = 6
*Arcanum = 9 ( and i havent played it much)
NWN2:MOB = 8 (not finished yet)
*TOEE = 8 ( only ever got about halfway )
*Civ 4 = 8
Bards Tale (remake) = 0 (cant even load it)
*Stronghold 2 = 6
*Morrowind = 6
Dungeon Siege 1 gold = 7
Dungeon Siege 2 = 8
thats just off the top of my head with my ratings.
games i bought that had a demo that i did not buy based on demo:
Bioshock
the main reason i buy games nowadays is based on what people say here or what they dont say here. or if its $20 or less in the bargin bin.
if they want me to pay more than $20 for a game, either it better be a game in a seriese i care about, or else it better have good reviews here.
i havent bought a gaming mag since like 2001 or so whenever that king kong game came out.
PS:
* in the title means i bought it because it was favorable here