Fixed the "Can't connect to the internet" problem: I ran into the same "Can't find the Internet" problem with a new Linksys WUSB54GC Wireless-G USB adapter -- running XP Home SP2.
We have a Linksys WRV200 wireless access point, and Comcast-supplied RCA cable modem. The cable modem and access point are running fine; three of our other computers were connected. I replaced an old USB wireless adapter on one desktop PC with a new Linksys WUSB54GC adapter. After the drivers were installed, Windows could "see" the access point -- with good signal strength etc. -- but couldn't connect to the internet. It apparently couldn't access the DHCP server on the router, and didn't retrieve an IP address.
I tried everthing, including the Linksys installation utility on the CD, removing and replacing the drivers manually, manually changes TCP/IP, DHCP and DNS settings, etc.
The solution suggested by Helm fixed this maddening problem: open a Command Prompt window and type: netsh winsock reset catalog <enter> Note: it can take a few minutes for your computer to respond after you hit <enter>; don't close the Command Prompt window.
To open a Command Prompt window, click on the Windows "Start" button, then click on the Accessories folder. The list of accessories will appear. Click on "Command Prompt". A small window will appear with a flashing cursor. Type the commands shown above.
Linksys should definitely add this to the FAQ list, to save users hours of frustration!