Be careful when buying hard drives what warranty you get with it. The exact same drive can be offered at different price points with 1 year or three year warranty. A few drives have 5 year. It's worth the $10 - 20 extra for the 3 year warranty -- because every hard drive ever made is going to fail - guranateed. It's just a matter of when. Year 2 and 3 are starting on the upramp of the ol' bell curve.
My preferred brands:
1) Seagate
2) Maxtor
The WD Raptor is expensive, fast, small capacity, hot and noisy. Unless you are doing mission-critical digital video or audio, $ no object, I would avoid these. But if $ were really no object I would be setting up an external SATA or UltraSCSI 320 multi-drive RAID system.
Whatever drive you get, spend some time thinking about how you are going to back up your data consistently and reliably.
Thanks
Trevor
CanadaRAM.com