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I will play DVD's so downmixing is a must... >>
You know that any software DVD player will do this for you right? The Live 5.1s don't have hardware Dolby Decoding, they just have a driver trick to do it in software....any good software player will do the same or better.
As for the card, the Live! line are OK but they are nearly 3 years old, and the analog output quality is very poor compared to the Santa Cruz and the Acoustic Edge (and from what I've been told Hercules is better as well, but I haven't used them myself). That's my only major complaint...after hearing the A.Edge's output quality it really puts the analogs on the Live! to shame. Sensura 3D on the Turtle Beach/Hercules cards is suppose to be pretty cool to, but I've never used it personally.
Personally I wouldn't get the live...it's old and outclassed by newer cards, but I've used one for 2 years and it's certainly not atrocious or anything. But if I were buying a card now I'd get a Cirrus Logic Cold Fusion DSP based card. That's the Turtle Beach Santa Cruz or the Hercules Game Theatre XP and Fortissimo2 I believe will be the same chip though it's not out.
The Turtle Beach is great for 4 speaker systems, and then it has a versa jack you can use as a dedicated headphone jack if you care about that

That's what I'm going to do with it.
The GTXP is like the SBLive! Platinum, it has a breakout box with all the audio connectors you could want.
The Philips cards are nice quality as well, and but they do weird things to wavs in 4 speaker mode. I've never actually heard QXpander in action...but I like my music un-processed. And as of now you can't turn it off

. Besides for gaming, Sensura3D is better than QSound 3D.
For DVDs you just need 4 channels output and a good sofware player so either works.
Music in 4 channel mode goes to the Cold Fusion cards.
Music in 2 channel mode is about even between Cold Fusion and the Philips chip.
DVDs are also about even.
Gaming would go to the Cold Fusion cards.
And the Cold Fusion cards have dedicated headphone jacks
So I'd get a Cold Fusion based card. The Game Theatre XP if you want the breakout box, the Santa Cruz if you don't.