I just got done reworking an old laptop, which suffered from a lack of a wireless card. The only ones I had were 802.11b and I had a need for something a bit fast, so I ended up ordering a Linksys wpc54g.
After some research I found that others have managed to get that card running. The key is to just go with the ndiswrapper and the windows drivers provided by Cisco and install them under Ubuntu 9.10 (Karmic).
I simply downloaded the vista driver.
That left me with a .exe, which fortunately is just a self-extracting zip file. So I simply unzipped the file and then installed the it the ndiswrapper way
sudo ndiswrapper -i wpc54g_v31_driver_18.104.22.168_Vista/Lsbcmnds.inf