Windows 7: Surround sound not working

Apparently I am not the first person having problems with surround sound in Windows7.

I have a RealTek ALC850 sound card, with 7.1 line out, Coaxial, S/PDIF out outputs and Creative T7900 7.1 speakers. I am only getting sound from the front left & right speakers and subwoofer.

When I use the RealTek sound configuration, every time I select 6 speakers, it automatically reverts to 2 speakers. When I try the Windows sound configuration I select the Surround 5.1 button. When I test the speakers however it always says they are being used by another application and the test failed. Hence, it always goes back to 2 speaker setting.

When I try and load the latest RealTek driver, windows says I have the latest driver. It's the same with the Troubleshooting.

In XP I simply plugged in the light green, black and orange plugs into the corresponding sockets, changed the settings to surround and everything worked fine. Now I have no sound from the rear left and right or centre speakers.

I am not a techie person, so if there is a fix to this problem I would like it in plain English with simple to follow instructions please.