I use FireFox too but I made the mistake of letting Windows Update upgrade to IE7 to be on the safe side. Big mistake... after the obligatory reboot I lost all networking - Wireless, Ethernet and Bluetooth. None of them could aquire an IP address. System restore didn't help. In the end I had to reinstall winsock using the instructions here:
http://support.microsoft.com/kb/811259
(Funnilly(?) enough you have to use IE to see all of that page - it's truncated in FireFox!)
I'm just posting this in case anyone else has the same problem.