Here is what I suggest at this point:
1. Boot your Ubuntu 11.04 CD in "live" mode
2. Run the Restricted Hardware Drivers app and activate the STA driver
3. Open a terminal and type:
4. Use the Network Manager to connect to your wireless network.
If that works, then you know it is possible
and you can choose to either troubleshoot your existing install or just do a fresh reinstall.
If that doesn't work then I'm out of ideas, sorry.