Well, HDtach is a popular one
gives u burst speed, acess time and a continuous transfer rate graph for the entire drive capacity.
judging by your kick ass system if you keep an older drive you are REALLY doing yourself a disservice.
i reccomend AT LEAST a 7200rpm drive and ATA100 otherwise your drive will be a serious bottleneck.
i have an IBM 40gig 60GXP. very fast and sweet drive. quiet too
i reccomend that.
I would show you some apathy, but i just cant be bothered.