When getting into Linux I did like Jim and James talk about.

I purchased a second hard drive to LEARN on. To make it easier to
change from one drive to the other I also purchased a "mobile rack".
TigerDirect and NewEgg, among others sells them.

This consist of two pieces:
1) The part that screws, bolts or otherwise, attaches permanitly in
the computer, the receiving frame.
2) The part that the hard drive fits into, the drive carrier. You
need one of these for each hard drive.

Now with the frame in the computer and each hard drive in a carrier,
slide the hard drive you want to use into the frame/computer and
boot-up.

The carriers have to match the type of hard drive, IDE, SATA, SCSI
and so on. The frame I purchases has a fan. Don't know if it is
needed but when the hard drive is in the carrier it is enclosed in
yet another container. It could get too hot in there.

Now I can go from Windows 2000 to Ubuntu in just a few minutes and
one operating system cannot screw up the other.

Although the drives are different sizes and different manufactures,
when changing drives I do not have to reconfigure the hard drive
settings done at power-up.