I wanna build my own computer but.....?

The main thing to keep in mind is to get the best motherboard and processor you can afford. And ram don't get nothing less then 1 gig of ram you can always upgrade that at a later time also. . You can get a cheaper video card and soundcard that can be replaced at a later time. Or find a motherboard with both built in to it. You can always upgrade the video and sound at a later time. If you do that with a little tweaking of the motherboard.