[RESOLVED] Restrict Internet Access

Can anyone recommend an application to restrict internet access on stand alone PC with ISDN dial-up access to an ISP?

I am looking for a simple piece of software that will restrict access globally to all web URL's apart from those on a predefined (Allowed) list.

I do not want a complicated proxy nor am I looking for content filtering (NetNanny, etc - overheads on the PC are too high).

I did find what looked like a piece of software that fitted the bill, but it works intermittently and also stops ASP based sites from working properly!! As the main web site I want these restricted machines to have access to is ASP based it is absoloutely useless!!

Can any one advise?