One thing i do is to buy a cheap external drive box, usually around $20 and every time i do a hard drive change at work or for a friend, i keep the old drive, i even have picked them up at garage sales for $2 and take them home pop them in the external box and plug into ta USB port and most of the time they read fine. Then format them and put them in a drawer for later. When ever i need a storage unit for back up pop one in and copy the data. pop it out and box and label it.
I have about four or five right now, and they are great simple storage. Mostly they are old 30 to 80 gig drives I have replaced out of a system at work where the boot up sectors are corrupt. They still open up as slave drive nicely.
My favorite is a 40 gig laptop drive i replace in my old Compac with an 80 gigger. It is in a small external box and i use it to shuttle from computer to computer.
Here is a great place for purchasing backup drives, for the less brave.
http://www.geeks.com/products.asp?cat=HDDFunny thing is i live about 4 miles from the outlet for Geeks.com, they have tons of cool stuff
here are the drive cases some real nice prices.
http://www.geeks.com/products.asp?cat=CSE