First question: Have you tried rebooting the router?
Second question: Can wired computers surf?
If the answer to #1 and #2 is yes, then I would try resetting your router back to factory defauts and see if the wireless end works. If so, then I would set it up with whatever security you had on it and see if it works after that.
If that doesn't work, perhaps you have a dying router....
ACDT, ACPT, MCSE 2003, ACSA
MacBookPro 2.66 Ghz Core 2 Duo (Mid 2009) W/OSX & Vista, WinXP, Win2K via Parallels, 8GB iPod Nano W/Video
I work on the dark side because the pay is better than what I could get the Apple world. Sad but true