Is it possible to limit the total time a user can be logged in on Windows XP Pro?

Is there a way to limit the total amount of time a single user can be logged into an account on Windows XP Pro? I'm looking for some way to specify that user X can be logged in for N hours a week and possibly warn them when they are running out of time. I've poked around a bit but haven't been able to turn anything up.

I'm not particularly interested in limiting the amount of time for a single session (unless of course they use up their entire allotment in one go) although that is a possibility if I could limit the number of logins per day as well.

Can this be done natively or does there exist a third party app that enables this?

As the tag indicates this is a home use question as I'm trying to find a solution to ration my kids computer time this summer when they are out of school but I can see the solution being of interest in other shared resource environments as well.

several of my users in this situation have had good luck with this program:

http://www.pchomesoft.com/kta/index.html

It provides for a fairly insane amount of customization, including limiting the number of hours per day the computer will function.

In the past I have handled this issue three different ways.

One, Microsoft ISA server. This solves a couple of issues.

• you can limit the time the youth are on the internet
• track what they are viewing and course correct behavior
• throttle the speed that hey are able to surf

Two, Router that has login and filters This is almost like internet cafe software but done at a hardware level

Three, when the above two attempts at a technological solution failed I reverted to a good old fashion power timer under the desk. I put it all in a lock box and when it was time for them to be off the computer it went "Click" and there was no computer to be using.

The last was the most satisfying as a parent, the cheapest, and was full proof.

You could write a VBS logon script for their XP account. Something that ran in the background and would force a logout or shutdown when a certain time of the day was hit.

In an effort to get my brother to play less WoW and go to school I put a scheduled task on his machine, which would fire every 5 minutes from 11:00pm to 8:00am and shutdown the computer.

He eventually figured it out, but he was pretty frustrated for a month or so why his computer would suddenly stop working late at night.