What Sersoft says be true.
Secure is good! But not all adapters are as standard as you may think. I’ve spent long enough pissing about with wireless devices (even with my belkin gaming adapter) to know the frustration the uninitiated must feel.
First thing I’ll ask is, did you reconfigure you’re madcatz device?
(if not that’ll be your problem)
If haven’t, find your installation cd (or download it) and reconfigure to match you settings!
What if your madcatz device doesn’t support WPA?
Set your router settings to WEP, and see if your Madcatz supports that.
If it doesn’t, you’re going to have to buy a new wireless device, or turn of the security on your network.
What if it does and your xbox still won’t connect?
Make sure you’re not in a mixed mode on your router. For some reason some devices do not support mixed WPA/WEP modes on a router (one of my PDAs doesn’t) so you’d have to go into pure WEP mode, not mixed WPA/WEP mode. I’d concentrate on getting the madcatz to connect, PCs will basically connect to anything.
If this doesn’t help, feel free to PM me, when I am more sober I will PM back and try and sort you out, if I can.