I would go for a Maxtor Drive or an IBM if you have a little extra cash. Very good.
Used Maxtor for many years and never had a problem.
WD drives are ok, never used seagate.
Also consider that there is new technology now or very soon Seral ATA which will have faster read/write performance. 150MBS to start but up to 600MBS so I am lead to belive. Dont know how much these will cost or if older mobo/BIOS will support them, but there should be a PCI card to interface with them.
Im sure that there is someone on here that knows more about it.