I used to always use Aria, as it was local to me, and has grown massively over the years, they always have 'super specials' which last for a day, it's best for oem boxes (just the basic hardware in a brown box, as supplied to computer shops)
computer hardware, components, systems and peripherals at the lowest prices from IT supplier Aria Technology
also theres dabs
dabs.com - Laptops, Components, MP3 players, Software, Digital Cameras
I used to really rate lacie, but had a hard drive with an awful 5 pin power plug, i guess it split it into 12 and 5v in the powersupply. anyway the plug broke after about 3 months, i was working on something at the time so had to prise the box open and stick the hard drive into my computer. but generally they're good and i think that plug is obsolete now as most are powered from USB. I replaced this with a freecom which is now getting rather noisey (I do transport my drives alot), lacie have a good reputation, everyone i know editing movies (very hard drive intensive) seem to use lacie external drives.