If it is WIFI certified...
- look for the WiFi logo on the NIC
- see http://www.wirelessethernet.org/index.html for more info
...then it should interoperate
You will not be able to use Cisco value-add features such as load-balancing, world-mode, and LEAP with a third-party NIC however. (Apple NICs do support LEAP).
WIFI certification only requires 64 bit WEP so you may need to check if non-cisco NICs support 128bit WEP keys if 128bit is required.
