[QUOTE=coolcolors;2480533]HDD for desktop in 3.5" go for 7200rpm…never go with 5400rpm. I say go for WD carvier blue 1TB or black 1TB. I have the black version and it’s working good if not better then I expected.[/QUOTE]
Generally speaking, I agree. But the OP has to also consider what he will be using that old Socket 939 AMD-powered PC for: If it is to be running games or video editing software, then he would need as much hard drive performance that he can get (especially now that 1TB 7200 rpm drives cost only a few dollars more than same-capacity 5400 rpm drives with the same amount of buffer memory). However, if that older PC is to be used primarily as an HTPC or a Web/office-apps-only PC, then 5400 rpm would suffice.