OK, so when you uninstall the driver, then there is Sound going out to the TV - but after drivers are installed, then there is no sound.
Do this - Get
Guru3D - Driver Sweeper (Setup) download from Guru3D.com and install it - reboot into safe mode - run it - remove all traces of RealTek - reboot - let Vista load the default drivers - see if sound works. If not install the latest 1.97 drivers - see if sound works.
If not, then open the sound control panel and click the lowercase letter i in the bottom right corner and make screen shot of that.