I can connect through my linksys wrt54g wireless broadband router just fine, I dont do it wirelessly beacuse thats just a pain in the ass. Try swiching over to a static ip for your xbox?
You have to do that manually in the router settings, I think for linsys routers the ip is umm...192.168.1.1? And if you havent changed the pass it will be somthing like User: Admin Password: password
Then all you have to do is check it from DHCP to STATIC and get the right information. Give your xbox a set ip through the router, 192.168.1.5 for example. The downside to this is you have to swich all the computers to static as well, meaning they will have their own set IP's that they request from the router. I used to be on static, but decided my router was doing a good job assigning my ip.
If you dont wanna try all that, just take a look at all your router settings, and make sure you enter it on your xbox, and then see if you can connect.
And if your blonde, are the cables plugged in?