Well the _easiest_ thing to do would be to get a copy of Partition Magic, which will do just fine at chopping that Windows partition down to size. It has a graphical interface, and will run from Windows. However, it'll run you anywhere from $30 (online) to $80 (CompUSA).
The second _easiest_ (but still easy) thing to do would be to try a different distribution. Mandrake Linux and (I believe) Suse, come with a utility which can resize Windows partitions. This utility will be run as part of the installation.
The much more adventurous route (but no longer easy) would be to download a live-CD distribution, such as Knoppix, burn it to a CD, and then boot from said CD. You may then use a Windows-partition resizing tool that comes on the CD, such as QTparted (graphical) or ntfsresize (command line).
The live-CD approach is a great way to try Linux without committing to anything at all, as it is a complete distribution running off of one CD. Just remember, it runs slow because 1) it's loading from your CD, and 2) everything is super-compressed. A _real_ installation of Linux is really quite fast, and can breath life into aging hardware.
Whichever route you decide to take, you know the story.... be sure and back up all your important data. Chances are, everything will be okay, but you can never be too safe. Well, yes you can, but backing up your data has never been known to create an excess of safety. Oh, unless you use the live-CD -- then backing up would be an excess of saftey, as this method doesn't even touch your existing configuration.
Good luck! And have fun! Linux is fun! Yes!