20 open computers i need to block the porn?

okay so i work in a place where the public can come and access the pc's for free and print resumes and all that but there's this one freaking kid that comes in a all he does is look at porn and other nasty crap on the pc im sure it isint all him but so far he's the only suspect i have.

all the computers except for 2 run on windows xp and the internet explorer is the internet browser i dont want to have to kick the perverted little punk out id rather just get all porn blocked or anything that might have porn in it.

anybody know any ways i can do this it can be for money cause we are non profit (sooooo all the good programs you can buy are kinda outta the range right now)

(and sorry i dont feel like spell checking im to ill and annoyed lol)

20 open computers i need to block the porn?antispyware

http://www.brothersoft.com/porn-filter-4...

20 open computers i need to block the porn?best antivirus software

strongly recommend NetDog Porn Filter : http://www.netdogsoft.com , netdog blocks all porn quitely in the background when anyone's on the computer.
Try a free parental control program called K9 Web Protection.

Here is their Description:

''K9 Web Protection is easy-to-use Parental Control and Internet filtering software that helps parents protect their children online. K9 Web Protection has the ability to block adult, porn and other offensive content, prevent spyware infections, and monitor visited sites on any Internet access connection (AOL, MSN, Yahoo, Earthlink). Based on commercial-grade Web filtering controls from Blue Coat Systems, K9 Web Protection is unique among content filters and it is free for home use. K9 can be configured as a porn blocker, a spyware stopper, a gambling filter or various other configurations based on our over 55 Web categories.