Thrush,

3.5" will need external power, only laptop drives (2.5") can be powered off the USB port and even then, I've seen 80Gb ones not power up properly.

But, £30 for a 60Gb drive
You can get a hell of a lot more for that money, £60/70 will get you close to 250/300Gb iirc

And what good is a 60Gb when you have 300Gb of porn to backup You're going to spend months trying to figure out which movies you REALLY want to keep.

This one, no that one, ah, but this one's quite cool, etc............

Try Dabs or eBuyer for a case, I can't think of anything to look for specifically