Accessing wireless with Vista and Intel wireless

We are having some issues with browsing the Internet via wireless on Vista
computers. The computer connects to the access points and is getting a valid
IP address, but isn't able to browse the Internet. OS: Vista (doesn't matter
what version); APs: 3Com; Wireless Cards: Intel (different versions); PC
Make: Any. On "home networks" everything works fine. We found a "work around"
by installing the latest XP drivers for the wireless cards on Vista machines.
Everything works just fine then. Does anyone have any ideas what the source
of the issue might be? Thanks for any information.
Chris