Well, if you want a card for a HT system, its very hard to argue against the Auzentech Home Theatre HD. You get HDMI In/Out, Optical, and 7.1 Analog to choose from. Still, it is overkill if you don't need to have a combined Audio/Video HDMI output to a receiver of some kind...
-)HT Omega Striker [budget]
-)Auzentech Meridian 2G [All around price/performance]
-)HT Omega Claro XT [Best in class]
-)HT Omega Striker*
*There is no need to get a better card then this for use of the optical out, as the device at the other end handles the decoding. If you may use the analog outputs later, you can move up to another card, just ensure either DDL or DTS-C is supported on the card in question.
-)ASUS Essence ST
-)HT Omega Claro XT
*All these cards have a built in amp, so they favor headphone use. The Essence ST only supports Stereo analog output without the H6 card connected though.