Here is a great explanation on how to set up parental control on Vista.

http://www.bleepingcomputer.com/tutorials/tutorial...

Here is a good step by step tutorial:

http://www.delete-computer-history.com/parental-co...

here is a tool i am using for parental control, u can take a look if interested:

http://www.keylogger123.com/power-keylogger-for-ho...