If you really want to "try" Linux, I suggest you try Knoppix (
www.knoppix.org)
Its boots from a CD and has a good range of applications so you can get a nice feel.
Best of all, you don't have to do anything to your hard drive. Don't like Linux? Unmount the CD, reboot, and go back to Windows.
Like it? Bust out a partition manager and make some space for your new OS.
Go nuts!