Question : Automatically detect and change Internet Explorer Proxy settings when on other Networks

OK I'm new here so here it goes.....
At work we have users who work externally in the home offices, we supply them with broadband and a laptop with polices that lock them down. Now when using there laptops whilst plugged into the broadband there is a proxy address in there Internet Explorer settings so there Internet activity can be monitored and certain sites\files restricted. This is done through my isp, as they supply a system that allows you to register the public ip supplied on the broadband with the web filter then you can setup rules for that user.

Now the problem is when me users take there laptops away on the Train etc. for instance when you go on the train even though it's free broadband you still have to load up your browser once connected and register your email address. Then you will get a connection to the internet. But because of the proxy settings in Internet Explorer I cannot access the web as it's trying to proxy an unknown address to my isp's web filtering server. So my users in some case are stuck without a connection.

Now I would prefer not to give any of my users and access to the proxy settings, as they would abuse this.
I have thought about giving my users access to the proxy settings, and then blocking ports http and https on there home router. That way if they thought about not putting the proxy address back in then they would not get normal none filtered Internet Access and they would have to tick the proxy address back in Internet Explorer.

Any suggestions guys? I have looked at some third party software but it would need to have lock out cababilities. I thinking a peice of software that will automatically detect that its on a different network then remove the proxy settings and then when it detects that it's back on the home network, puts them back in. I maybe thinking to technical about it, that's why I've made this post as everybody seems really clued up on here.

Sorry if I've rambled.

Many Thanks in advance
 

Answer : Automatically detect and change Internet Explorer Proxy settings when on other Networks

There is a document called: Managing Roaming User Data Deployment Guide (Windows Vista)

http://go.microsoft.com/fwlink/?LinkId=73760

Configuring Roaming User Profiles can be a useful document for users connecting to your Win2K3 server:
http://technet2.microsoft.com/windowsserver/en/library/b41402c2-c982-4bfb-891e-91b47f211e181033.mspx?mfr=true

Hope it helps.