WDs and movies=OK
I have 2 WD 1TB drives that I use in a 2.1 GHz Dual core AMD 3800+ w/3GB RAM to record, edit and play back videos. Things are working out pretty well with this setup, possibly due to my running XP Media Edition but certainly not failing to provide smooth video because of the hard drives. Quite often, I record broadcast digital TV through a Pinnacle PCTV USB adapter while I continue to do other work, and the recordings are usually smooth unless reception is otherwise hindered by a weak signal. When I used to record from a cable TV connection (through the same Pinnacle adapter) reception was almost always flawless, as were the recordings I made.
Generally speaking, I testify that WD drives are not incompatible with either recording or playback, and with sufficient RAM and processor speed, allow simultaneous work of other kinds.