Sorry if these questions have been answered here before but it seems all the sound card discussions are a year old or don't address my questions specifically.

I want to integrate my HTTP into my existing home theater set up. The video will be sent to either my current 42" plasma TV or the soon to be finished Projector. and The audio will be routed into my Dolby digital/DTS denon receiver either through the RCA style digital input or the optical digital input. Now for the questions. Do the digital outs on most budget sound cards like the Sound blaster 5.1 support Dolby dig and DTS? or is it just passing the digital out through the card from the DVD player? And if thats the case is it the DVD drive that has to support or not support those formats?
The DVD drive I'm using is out of some old HP machine its dated 1999 and the model name and number are:

MITSUMI CD-ROM DRIVE MODEL NO. CRMC-FX4821T IT HAS THE STANDARD DIG AND ANALOG OUTS.

MY Motherboard is the Abit a17 with a built in sound chip thats says it supports 5.1 ch out via 2 sets of stereo 1/8"jacks and 1 sub 1/8" jack or an optical digital out.

my other choice is the previously mentioned basic sound blaster 5.1.

I'm not going to be gaming on this machine I'm using it just for the PC's powerful upscaling.

So.... Whats the deal on the surround sound?

I just though of something I use Windvd Platinum and I noticed the DTS and Dolby Dig logo's on the skin graphics. Dose that mean Its all in soft ware and the sound cards don't matter? Getting more and more confused.