Earlier advice to go to http://www.distrowatch.com
is the best advice. I've never had much luck with distro supplied versions of gparted. I prefer getting Gparted, pmagic, or system rescue cd from distrowatch. This way has been less problematic for me
Also, if you're running Vista, Some extra care should be taken as Vista has a couple of partitions. I've never fooled with Vista so I don't know what precautions to take. I come across posts about this while trying to fix problems I was working on at the time. Just putting the bug in your ear so you won't mess up.
I dualboot Windows and Linux on a couple of my machines and it's easier than it sounds.