I have the same problem, except mine is on Windows Vista. The device shows up correctly in the device manager, it's installed properly, drivers are updated, and I downloaded an update specifically for the device for Windows Vista. Still, the card doesn't work and when I try to add the PC to the network, it tells me there's no wireless adapter, despite the fact that it's installed, shows up correctly on the list of devices, says its working correctly, and it's lit up. And when I install/reinstall the drivers listed above, it tells me "Wireless Adapter not found, please insert adapter now", despite the device being lit up and shown as working correctly in the device manager.
The funny thing is: I'm installing it for my mother-in-law, so after it wouldn't work, I put it in my PC and, after installing and seeing it wasn't working in mine either, I screwed around with it until it finally worked. So, now it works in mine, but not the other (newer) PC, for some reason :/