HP Simple Save Portable HD/320gb 2.5 Inch USB2
I have now owned one of these for 6 months and cannot fault it. I use it to back up three desk tops and two laptops. Two of the desk tops are five years old (a Dell and a Packard Bell both running XP) and have had no problems what so ever. I was really pleased, when shortly after buying it an ageing Acer laptop (also running XP) decided to turn up its toes and because we had everything backed up on the Simple Save we had an easy task transfering all the data etc to another machine (the aged Packard) without any apparent loss.
It can take a while to do the initial backup for each machine (it creates individual backups for each machine so it's an absolute dodle to retrieve anything) after that it just adds anything new that you have saved on the computer, which if you backup once a week will take a couple of minutes. During the process it shows you the type, number and size of file that it is saving fr you. I have encountered no issues using the Simple Save with Windows XP, Vista and 7 (we have a laptop running Vista and a desltop running 7). Its instalation and operation are as it says in the name, simple. it is light weight, portable and is a smart looking unit.
I like it so much that I have just ordered a second one to be exclusively used for my work laptop.