Boot a live Ubuntu CD and TRY it. You don't have to erase Windows to try Ubuntu - just download the CD from www.ubuntu.com, burn the ISO file *as an image* to a blank CD, then boot that CD on your computer. When it asks, choose "TRY UBUNTU" and *not* "Install." Ubuntu works great off of CD without touching your hard drive - it's just a tad slow that way. But at least you can take it for a test drive.

If you like what you've seen after playing with Ubuntu on the live CD for half an hour, go ahead and install it.