Consair seems to be the most often reccommended PSU company. You might not want to go AMD right now the AM3 socket will be dead in about two months. Check out this article for cpu ideas: http://www.tomshardware.com/reviews/best-gaming-cpu-cor...
The g-skillz ram kit previously suggested is a great cheap starter kit.
The HD 5850 can be had for $140 shiped from newegg right now which seems like a great deal. This one has 1440 stream processors compared to the newer HD 6850 with only 960.
GPU, it depends upon the Game(s) you play and the resolutions you use. Therefore, if the Game(s) you play can be played at 40~50+ FPS with the HD 5750 then you're good; I doubt that's the case but unless I/we know the Games & Resolution who knows.
In addition, Games should be played at 4xAA or higher so whatever benchmarks you look at look for 4xAA or 8xAA.
I don't want to go over $1000 for everything (burners and cooling) as I'm pretty much broke at the moment. But I mostly will use it for HD movies, photoshop, word processing and games like call of duty. So pretty much an all rounder.