InfernoBanana, I think you'll need to go with a Hauppauge card (the Theater, HD or D ranging from $99 to $199) to get real 5.1 sound... I'm not sure if they include a PVR or what the capture limitations are but check out
www.hauppauge.com for more info if you're interested. If your audio card supports it, you should be able to emulate surround sound 5.1 (or 4.1 or what ever). But typically, tuner cards will be either stereo or mono.
I'm really leaning to the Asus even though it has two 9 bit ADCs instead of the 10 bit ADC on the Expert. I believe the Leadtek to be a better product but I think the Asus will provide a more complete package. Finding reviews on the Asus is near impossible though!