$800?
I'd wait a couple weeks (months?) unil you've got about $1000. At that point, your options open up wide. That said, get this or something like it:
http://cincinnati.craigslist.org/sys/108748953.html
That will do awesome with iMovie and you'll be set with a kick ass LCD and a pretty sick computer. Just buy the new version of OSX (tiger) and you're golden.