So many hard drives out there are up to the task...
You should check out places like Storage Review if you really want to look at numbers for individual drives.
Also, note that SCSI drives don't have the performance advantage that they used to years ago.
Also, note that USB 2.0 requires more CPU over head than firewire or IDE or SCSI.
For me, personally, I look at sound and reliability above all things. Since Seagate recently upped all their hard drive warranties to _5_ years, unless other manufacturers match that, Seagate is going to be my choice for my next hard drive. The fact that they have a reputation for quiet puts them a notch above the competition as well. Samsung was also one of the few hard drive manufacturers to stick to three year warranties when practically everyone else went down to one year. They're not bleeding-edge performance oriented, but they've always been consistently quiet running and low-temperature.
I've actually been using a 5400 RPM Fujitsu for some audio tasks for the last few years and it's done me no problems. That doesn't keep me from using the latest Seagates, Hitachis, and Maxtors in my setup, though...
I'm still on regular ATA 133, and I'm not going to get an SATA hard drive until my motherboards require me to get one...