filtering ideas

Hi folks
I have set up a windows 2000 server and a copuple of labs of about 75 computers. they are connected to the internet via ICS and DirecPC. I used to use wingate and set up blocks for inappropriate site but can't do that in ICS. DO any one you know of software or a way to block site, on the cheap? thanks
Brent

Set up a proxy server on that windows 200 box.


Something like these?

http://www.ntware.com/server/s-_proxy.html

(Never tried them, just googled them.)