To answer your question...yes!
If by "Home Theater" you mean a receiver then you will have to use the SPDIF connection. It can come in a few forms: Optical cables known as Toslink or regular Coaxial cables or HDMI (which can carry audio or video).
As far as I know, the sound card on your motherboard does not matter if using a digital connection to receiver because SPDIF bypasses this by sending the raw signal to your receiver which has its own SoundCard (also known as a pre-amplifier) and does its own processing.
If your receiver supports 5.1
If your source support 5.1
and if your motherboard has one of those three digital connections
Then you're set for 5.1!