The ultraportables are some of the most interesting improvements being made now. With the "X300":http://www.pcmag.com/article2/0,2817,2270393,00.asp out now, you can really make a comparison. The long and short of it is that the X300 looks like a PC rather than a style marvel and has a solid state disk like the MacBook Air option. It does use a low voltage processor, so is about a third slower than the MBA, but it should have better battery life and of course it has a DVD. More importantly it has an EVDO option built in. This is probably what I miss the most about the MacBook Air. Wifi just isn't everywhere and it would be nice to have a 3G modem option.
"Geek.com":http://www.geek.com/thinkpad-x300-the-full-review/ agrees adn notes that it is nice to ahve three USB ports as well. You can stuff a 6-cell battery in and get 5 hours or take out the DVD and get up to 7.5 hours. The main drawback is that 64GB is a bit small for most operating systems.
Net, net, if you have to have a PC, this is the ultraportable to get. As I've told folks before. If you can hold out at all, please wait. The real miracle here are the solid state drives and this coming fall, they are really coming out in force. Will make the 80GB in the MBA and the 64GB in the X300 look tiny and way expensive.