Media for Wireless Internet Stopped Working

Wireless Internet Stopped Working

Please help me, tech gurus!! I have a SONY Vaio (PCG-TR1A) and a Linksys Router - WRT55AG. The wireless on the laptop has never worked all that well -- the connection used to cut out frequently, but repairing it usually did the trick. Now, it will not connect at all. I can see all the available wireless networks including mine. I hit connect and it just says "Waiting for the network" until it tells me it is unable to connect.

The connection is fine when connected directly with a wire.

A newer Gateway laptop in the house works perfectly wirelessly and has no problems. Thus, it is not the router.

I have WEP security enabled, but I have tried disabling the security and have the same problem, so that's not the problem.

I have tried disabling the Windows firewall.

I have tried disabling and then reenabling the wireless network; I have reset the router.

Does anyone have any suggestions? I'm completely stumped.

The computer is running Win XP with SP2 installed.

Thanks.