I just did research on spell check for vBulletin, and it really isn't a feature here. Weird, considering all the other great features they have!

There are hacks I can install, but it requires a lot of coding and I'm scared. (CC: are you more confident about this stuff than I am?)

Meantime, I've found a solution for anyone who's using Internet Explorer:
http://www.iespell.com/

That's a free spell check that'll work in Internet Explorer on any message boards, chat rooms, etc.

(I use Netscape, so no good for me. Others, let me know if you like it!)