Tweaking internet access on LAN connected through dialup

I have a small network at my home. There is a windows 2000 Advance server on one machine and there are a couple of Win98SE machines.

I have shared my dialup connection for networking in win2k. So far, you can access the internet from the win98 machines.

What i intend to do is to restrict internet access on the win98 machines based on time. For example allowing only 4 hours access in a day or access during a specific time period etc.

What would be the best way to do this? Can i do this without the help of 3rd party software or not? If not what would i need?

Thanks...

You'll need third-party software to do this. I'd recommend something like Kerio WinRoute Firewall - it should do all that you want and is easy to setup.