I'm not aware of many compatibility issues with WLAN cardsin W7, but I have a Linksys Wireless N PCI card on my W7 for over 3 months now and I haven't had a problem with it yet.
I had a problem with my(now broken) Abit airpace once.
The driver used for VISTA x64 didn't work and I have to use other driver (Atheros) as recommended from someone in this forum.
I have been using Win7 for months and no problem appeared...
My card worked fine until 2 weeks ago... so I guess..it is broken..
Then I searched in various forums...many people are having problems with the drivers for Win7 x64...
And I couldn't find any new Abit Airpace in stores near home...So..I think it is better to ask before buying