Got a free PCI slot? I just installed one of these recently,
Newegg.com - TP-LINK TL-WN851N Wireless Adapter IEEE 802.11b/g/n PCI Up to 300Mbps Wireless Data Rates 64/128/152 bit WEP, WPA/WPA2, WPA-PSK/WPA2-PSK (TKIP/AES)
in my kids upstairs computer and have had no problems with it at all running on 7 x64. Only thing I had to do was install the driver for it, which I used the latest from TP-Link instead of the one on the disk.