i have windows server 2003 with windows xp for clients . i need to disable internet access for some users and enable it for the others, and i need all users can open IE cause i have some elearn videos on my network how can i do that ?
Do you mean for some users, or for some computers?
If it's users you'll struggle without third party software or hardware.
If it's computers, the best/right place to do it is on your firewall/router, or depending how your network is structured you may be able to get away with simply not setting a default gateway on the clients you don't want to have internet access.
We need more info really.
The simple (imho awful hacky) way of doing it is to lock down IE so users cannot change Internet Connection settings, then use group policies to push out a bogus proxy setting to the people you don't want to have access, with additional settings to bypass the proxy and access the address of the server hosting your videos directly.
The more structure (imho "proper") way is to actually install a proxy server and point all clients at it, and use settings on that to determine who can and cannot access what.
How important is it to stop people having internet access? In both the above cases its fairly trivial to get around the block by using another browser, unless you make changes to your infrastructure to make sure that all web traffic physically has to go through the proxy because that's the only route outside. At that point though it starts to be a lot of work and not something you should undertake without a proper understanding of what you're doing.