I totally agree with Mikey, You can get Optical cable out from PC to your receiver.
Afriend of mine has the same set up and it works great.
For gaming, I was told to make sure your HDTV has good enough refresh rate.
8ms or less is considered good.
Alienware used to make good Gaming PCs with MCE set up, but I'm not sure if it changed since they were bought by Dell now.