I use the following product and I am very pleased with it's performance.
I think it was around $30.00
(As copied from the help file):
KidsWatch Time ControlTM is one of America’s leading parental control
software packages that allows you to limit and control the time your
children spend on the computer, access the Internet or play games. Time
Control helps you block installation of unwanted software, prevents overuse,
and allows you to balance your child’s day.
With KidsWatch Time Control you can:
· Limit Internet surfing, chatting and game playing to a time and
duration appropriate for each child
· Schedule the number of hours each child can use the computer, per
day or by week
· Automatically log your child out of their computer when it’s time
for lights out
· Block younger siblings from gaining access to the Internet
· Lock down the computer to prevent your child from pirating music
or installing inappropriate software
· Easily share computer time among siblings
The combinations are endless! Mix and match the time, duration and program
options for each child and create the schedules that suit your family’s
needs. KidsWatch Time Control helps you have command over the time and
activity your children spend on the computer and the Internet. Help your
kids stay away from trouble and take the next step to parental supervision –
computer supervision.
http://kidswatch.com/
P.S. I am not affilliated with the company in any way; I just like their
product. I do not get anything for reccomending it to you.