Thanks for all the helpful feedback.

Right now, I have the HP2510P, Lenovo ThinkPad X61, Lenovo 3000 V200 and Dell M1330 on my list. The 3000 V200 in particular has been atracting my attention. The base price is only $1K and it comes standard with a DVD drive, webcam with a large HD (160GB), 1.5 MHz Core 2 Duo processor and 2GB of RAM. The downside is it's 4.3 lbs with the 6 cell battery...not quite a true ultraportable but significantly cheaper than the others and with a lot more to offer under the hood. Kind of sounds similar to the HP Pavilion.

Is purchasing in the US something to consider? The IT department of the company I work for said they'd be happy to purchase the computer for me, allowing me to take advantage of our corporate discount (I'm guessing $100 -200?)

I've kind of passed on the MBAir and the R500. I guess it's more not wanting to pay a $1K premium to lose one pound. I'd probably select the X61 over either of those.