Power Supply - anything with or over 400W (trust me, lots of the new things use up quite a bit)
Processor - c2d if u can, if not just an amd dual core
Motherboard - any mobo that supports things that you're plugging in
Video Card - 256 + mb ones, right now i think geforce 7800 is more in ur price range
Sound Card (5.1) - not sure, depends if u want quality sound
TV Tuner Card - never used one so i dunno
RAM - minimum 1 gig
(Corsair FTW!)
HD - i'm sure you can do this one yourself lol
note : make sure you can plug your monitor in your video card lol and make sure all your stuff are all compatible with each other