You can even taste Linux with no commitment by using a LiveCD:
http://www.livecdlist.com/
Download a CD, burn as an ISO, and simply boot into Linux from the CD. No modifications are made to your system at all. After you're done, you take out the CD and then reboot, and you're back to Windows. If you choose, you can usually install from the LiveCD though it varies depending on which distribution's LiveCD you're using.
Recently, I installed the latest Debian (stable's netinst CD) and it was extremely easy. After burning the CD, simply insert it while still in Windows and the installation takes it from there. Let me know if you want the URL for debian's installation CDs.