Hi!
There is an apache module named mod_throttle which can cap how many kilobytes (or whichever measure chosen) per second that your webserver sends.
http://www.snert.com/Software/mod_throttle/ will provide you with download and installation instructions.
Enjoy!
-Dave
Edit: P.S. This is for apache 1.3.x only, sorry if you're on 2.0.x :-)