I signed up to play intramural squash against other dorms at my university, but I have absolutely no idea how to play and I'm having some trouble finding a set of simple, basic rules online. Can anyone help me out? I've never played racquetball and I've seldom played tennis, so I don't really know any of the terminology ...

Try this one CD
http://www.us-squash.org/squash/x000610oRules/x0410oabbreviatedrules.html

If it doesn't tell you exactly what you're looking for, it might give you a starting point.

Cellardoor, I use to play a lot of Racquetball and Handball in college but never Squash. I have watched a few games and it is definitely fast paced and it looks like a lot of fun. Compared to Racquetball, the obvious difference is the size and shape of the racket. Sorry I was not too much help, click on the link, wait a about 15 seconds and play a game.
http://www.middlebury.edu/~schar/java/Squash.html

Thank you both. Leprechaun, the rules link was very helpful, and I had a lot of fun playing Wooldog's game (though I think I may need to work on my reflexes).