ndiswrapper is a Linux wireless wrapper that takes Windows drivers for wifi devices and makes them run on Linux.
So all you've really go to do is install ndiswrapper, then get the Windows NT driver for your card, then point ndiswrapper at it.
I'm about positive that Ubuntu comes with ndiswrapper installed, so the extent of what you should have to do is open the command prompt and do a
Code:
ndiswrapper -i /path/to/windowsdriver.inf
From there, I'm thinking there ought to be plenty of GUI tools to walk you through locating your AP and such.
Here's a more thorough step-by-step, though I'm not sure you need to do all of it:
http://ch.tudelft.nl/~arthur/wpc54g/