Windows 7: Not picking up Optical Surround

I have a Creative X-Fi Titanium Pro Soundcard connected to Logitech speakers via optical cable which is running great on my Windows 7 64 bit with Dobly Digital, trying to set up Media Center and I can't get full sound, on the optical settings there is no sound at all, the only setting that i get sound from is analogue single plug but then I have no rear speakers.

Any help would be appreciated

Right click speaker icon in system tray, near the time. Choose playback devices. Choose the digital output here to set as default device. If you can't see it, right click in the middle of the popup and choose "show dsiabled devices" or similar.

thanks for the reply, when I do that I have two options, Speakers & SPDIF Out,

If I chose the second I get all system sounds but no sounds when playing music or watching tv, if I go into Supported Formats and click on test on any of the options i get the error that another application is using it and it won't work, I have to use the Speakers option to get everything.

Put it on S/PDIF as default. Then check the application settings within the software you are using to play or watch. They will probably having their own individual setting for output to use. Choose default in this case.