If you're on a Mac, get a Lacie. They're flawless and impossible to break.
Well, they work on PC as well. But I'm just saying, (in my experience) drives built for PC's have a habit of sucking HARD on Macs. Not true the other way around, though.
Plus most Lacie drives come with USB, Firewire 400, and Friewire 800 ports. Which is sweet.
Plus they look cool.
http://www.lacie.com
I swear by these because I bought a Western Digital external drive once, and it didn't even last 1 day before it started dropping transfers, and shutting down unexpectedly.
I've had my Lacie for over a year. It's split, so one part's formatted for Windows, and the other for Mac.
I've NEVER had a problem with it, and I've hooked it up to 10 or 15 different computers.
The built for thing is probably due to filesystem. Most larger external drives are pre-formatted or intended to be formatted with NTFS, which macs have trouble with. The other option is FAT32 which macs are ok with but no file can be larger than 4 GiB, and on a 1TB drive your cluster sizes are going to be HUGE, wasting alot of the space. Else it's just a standard mass storage interface to the computer, which is universally supported among all platforms.
Your WD problem was likely just a bad batch. Lacie don't the make hard drives themselves, just fancy enclosures. They actually use Western Digital drives in almost all of their 3.5" external drives.
I have a 250GB Lacie (WD inside) external USB drive that has been running literally 24/7 for nearly 5 years now, and it is still running perfectly, so another vote from me for lacie if you'd like =o
Since your budget is £100, I would say get that Samsung F3 1TB samsung (mine arrived, installed, it's insane fast and very cool / quiet too) and then a nice enclosure. You won't need one with a fan for an F3 drive, only 2 platters
If you will be doing video editing I'd recommend get a better internal drive for your laptop, USB 2's limits will piss you off (forget working in realtime with HD fraps video off a USB drive
)