IDE or SATA?
If SATA (II) then I can warmly recommend the
500 GB Samsung HD501LJ

(Samsung SpinPoint T166 HD501LJ 500GB SATA-II NCQ 16MB)
It's a discontinued model but still available in many shops
(the new version is I think called: Samsung HD502IJ, 500GB, 16MB)
The HD501LJ is the best HDD I've ever had.
It's really quiet and fast too.
But the best part is:
It always stays cool (~ 42°to 43°) also under really heavy load in my server and the gaming PC.
All other HDDs I have and had were usually going up to ~47° till 53°. And 5 to 10 degrees is enormous for me
