I'm considering spending $1000 or less on a laptop as well (hopefully less). I need it only for academic tasks--researching online, writing papers etc. It doesn't need to be a performance machine, or have a lot of storage, because my desktop can handle those tasks. My criteria, in order of importance, are:
1. Battery life.
2. Weight.
3. Wireless connectivity
4. Boot-up time (depends on OS, I know, but still...)
5. Multitasking capability (i.e. can I run 3 word documents and 20 firefox tabs, some of which are PDFs, at the same time?

)
I was looking at ThinkPads because I really like my old one--it's just a bit too slow these days, but I'm definitely willing to look elsewhere too.
Any advice?