I have a 40 G on my laptop.. a 60 and a 120 on my PC, and an external 160.. USB
The 160 saved my but this week, and my 120 crashed, and my 60 went dead.. almost everthing was backed up.. whew! When I upload all my work to the pc, or laptop, I also upload it to the external Drive.. It is so easy to lose a folder full of work .. I lost a shoot of a rock band on my laptop. ALso, My laptop fan went dead, cooked the heatsink, and now they are finding trouble on the motherboard! What next!
I was able to format the 120, had to ditch the 60, the laptop is still in for service(warranty) and the external still is cool.. I recomend 2 sytems for backup.. and external, and a internal.. and never do anything until you have 2 copies of your recent files somewhere.
And .. the external is awesome.. just open it off your My Computer.. and Drag and drop.. create folders, and you are set!