No drivers are needed, support is already built into the operating system. Just plug in and reboot.
Windows 7, Vista, XP, Server 2008 and R2 (32 and 64-bit)
Plugable PCI-e cards purchased as of 10/16/2012 are µPD720202 based and require the 184.108.40.206 driver package:
Plugable PCI-e cards purchased before 10/16/2012 are µPD720200 based and require the 220.127.116.11 driver package: