Another option for old computer parts is charity - here in Cambridgeshire (in the UK), there's a charity called Red2Green and one of there projects, called Reboot takes unwanted PCs, refurbishes, and then resells them at ridiculously low prices - 'WinXP PCs' from £99 or 'Vista PCs' from £149 (inc. 3month warranty, 17" CRT, keyboard, mouse, speakers and printer).
I'm even thinking of going there first, when I consider my next upgrade, myself.
I'm even thinking of going there first, when I consider my next upgrade, myself.