Here are some ultra portable models I personally used/serviced during my work as a systems admin.
The notebook I use right now is an IBM (not Lenovo) X31 - its about 8 months old, and it dose all I need it to do. it weights only 3.6lb has a 12.1" LCD with 1024x768 resolution which is acceptable. It is great for presentations (as I often used it for them) and it is very durable having a magnesium shell (I once had a 50lb kid stepped on it and nothing had happened). it has all the itsy bitsy toys like gigabit NIC and Bluetooth adapter, it accepts up to 2GB of ram, though only 1gig is installed at the moment. battery lasts for around 3.5 hours (depends what you use it for).
The cons: no integrated optical drive - you'll have to buy an X3 ultrabase (in which you can add another battery) or use an external optical drive like I do right now.
The machine has 2XUSB 2.0 and a firewire port, so it should be ok for that.
IBM released some successive models: the X40, X41 and the X41 tablet edition. While I did not have the opportunity to check both X41's I assume that they are somewhat similar to what I have right now. The X40 notebook I used a while ago, is a little bit smaller then my x31, it weight is around 3lb and it is one of the smaller notebooks on the market. the cons of the x40-41 series is their integrated video cards (Intel extreme graphics, BAH) and their integrated 256MB of ram (which limits your maximum installed ram to 1280MB.Other then that those are pretty wicked machines designed for mobile business users who need their notebooks to do what they are designed for.
The warranty from IBM lasts for 3 years, and by having the on site plan the stupid tech will come to you to fix (or replace) your machine. IBM will keep supporting their machines up to 2008 and then Lenovo will take over.
Another useful machine on of the lawyers used was the Dell Ispiron 300m, pretty wicked little machine roughly the size of an x31. it has the standard 12.1" LCD and a somewhat attractive blue shell (even though its cheep plastic and not magnezium) it has a decent battery life lasting around 3-4 or so hours. cons: integrated video and no optical drive.
Again, this module is replaced by the Latitude X1 notebook line that have the same problems as the IBM X40-X41 (integrated video, and ram and no built in optical drive)
One of my friends has a Fujitsu P7010, a wicked little notebook.
10.6" lcd with XGA, built in modular DVD-CDRW and weights around 3lb. It is pretty wicked machine that with only two problems: Intel extreme graphics and the usage of MICRO DIMMS (they are more expensive and hard to find). This little system is highly recommended and Fujitsu, unlike Sony still manufacture their products in Japan.
Whatever you do, don’t buy HP.
If you don’t need the latest module, consider purchasing either the X40 or the 300M, they are all worth it.