at the mo i'm considering a 300GB 16MB cache maxtor 7000 (firewire/usb2) or a 250GB Lacie d2(or whatevre they call them now) triple interface but has only 8mb cache. both same price. (£170).
need to see the build quality on both but i think the lacie is the one i want despite the cache
I use a Lacie d2 Extreme 500 Gb hooked up by Firewire 800 to a G5 works
great and it is fast, on benchmarks it only drags a few points behind the internal. Only had it 6 months with no problems so far.
I always recommend a Seagate Barracuda in appropriate casing (USB2, FireWire or both). Often slightly cheaper to buy seperately and the Barracudas are fast, reliable and VERY quiet...
I just purchased a rosewill external case (oxford911/usb2) from newegg.com, and a 250gig WD drive. Works great, and cheaper than "retail" external drives. Rosewill also seems to have a FW800 case. They look fantastic.