OK, what are the remaining parts that you need? I think you mentioned a modular PSU, a SATA based DVD burner and a good aftermarket cooler for the video card, correct?
As far as the cooler and sata burner goes, I think you are probably going to have to bite the bullet, so to speak, and get them new someplace. Most folks still use IDE burners and even if they didn't, they haven't been around long enough where folks would have a spare sitting around to be able to offer. Kinda the same situation with the vga cooler for the X1650XT. The one drawback to this card is that it has a slightly different mounting layout versus other ATI cards so quite a few coolers designed for the X1800/X1900 will not work. You have to almost buy a specialized cooler just for the X1650XT video card or look for a good aftermarket cooler that has a large multi-purpose role and some of these can get a little expensive. Trust me with this, I had two different ATI silencers, a VGA silencer, two different heatpipe coolers and several smaller copper based HSFs, none of which were able to mount the X1650XT.
Anyhow, a little update for you while I'm at it. I went ahead and did some cleaning and maintenance on the video card today. I removed the cooler, cleaned off the original factory thermal paste crap with Arctic Silver's Thermal Compound remover kit and added a fresh coat of Arctic Silver 5. That should tide you over until you get yourself a good aftermarket cooler.