Please remember, people... DACs do NOT matter if you are using the digital output.
This is the real advantage of the card. Optical output means you are getting a direct digital signal out to your Dolby Digital decoding reciever in 7.1 sound (backward compatible to 5.1 AC-3). Piss on the DAC in this configuration, since the DAC is not touched.
I'm amazed there aren't MORE Dolby Digital cards out there... especially from Creative. There are currently three contenders for Digital output - nForce 2 Soundstorm, Intel HD Audio, and VIA ENVY HT. Any other cards that say they support digital out is basically LYING - because what they actually support is 3x2 channel PCM (Creative) for gaming or no digital output for gaming at all. Unless your stereo has 3 digital decoders (like Creative Labs' special speaker sets), you will never get anything but 2 channel digital sound for gaming.
Older cards do support "pass-thru" for AC-3 off of a DVD movie played through certain DVD players, but this is merely a digital shuffle.
Games on "older" cards certainly can have 5.1 or even 7.1 channel sound, but it's output via ANALOG channels (or the aforementioned multiple PCM channels), meaning a rat's nest of cables to your reciever or amplified speaker set, and the signal loss/noise associated with that setup.
In short, this card is GREAT for those with a Dolby Digital DECODING receiver with an Optical SPDIF in. It will consume a few clock cycles during games, but if you are playing on a weak CPU, why bother with 5.1 audio, anyway?
Hopefully, Intel and VIA's chipsets will put the heat on Creative Labs (nVidia has taken a massive step back by removing DD support from Soundstorm products) to finally add USEFUL features to their sound cards... but on the other hand, they make a lot of money selling their special speaker setups to people who don't know better.