Wireless cards and Linux distros are, perhaps, the number one complaint about Linux on the desktop (closely followed by power management). Both issues are being assiduously worked on by Linux desktop organizations.
There are three flavors of Linux that I have seen positive things written about regarding wireless integration: Ubuntu, SUSE and Linspire/Freespire. You might try one of those to see if it does better. Also, if you do some searching on the Internet, you'll find lots of info on this topic -- it relates to the chip type used in the various wireless cards -- which means some brands of cards work better, so you might need to track down a different card. Good luck.
This was first published in August 2006