There's another thread about the same USB wifi device (but branded under another manufacturer) with similar problems connecting over wifi. So far, the only solution has been to remove all security on the wifi network.
This hasn't been tried yet, AFAIK - try installing the drivers in Vista x64 compatibility mode.
Also - what version did you download? Did you download the 184.108.40.206 or 220.127.116.11 drivers?