Try this :
You just have to install generic USB headset drivers and settle for stereo sound.
To do this on Windows 7:
-Go to your Control panel
-Go to Device Manager
-Expand "Sound, video and game controllers"
-Right-click on the G35 entry and click "Update driver software"
-click "brose my computer for driver software"
-click "Let me pick from a list of device drivers"
-select "USB Audio Device" and click Next, then restart your computer and you're good to go
To switch back to your original drivers with virtual surround sound, follow the steps again and just click "Logitech G35 Headset" on the last step instead of "USB Audio Device".