Everything on that list below the Prelude is a PCI card as opposed to PCIe, so that just depends on which socket type you have available on the mobo. Generally, PCIe is better but as far as the card performance goes, I don't know.
The Forte is great, but for strictly gaming it's a little more than necessary. I have a Bravura and it's been absolutely great for gaming. I'm using 7.1 audio and it sounds just fantastic. So far, every game has been able to fully use the 7.1 channel sound from STALKER, Crysis, Metro, Batman, Cryostasis, NFS Shift, Dirt 2, Mirror's Edge etc. The only game I've had any issue with is Starcraft 2 beta, but it's a known issue. Basically, in the game menu you can only use stereo output. It has nothing to do with the sound card.
As for the Prelude, it is also a great card. It's basically the same as a Bravura. I'm not sure how many features are different but it should perform just fine in games. Looks like it has a few different input/output options.
The Forte and Bravura both have very high quality full-size headphone jacks which is great if you use a high quality headset. For speakers any of them will be good.
Here's the list from Auzentech http://www.auzentech.com/site/support/comparison.php
I have the Forte and i'm very pleased with it.
I don't know how much better it is at gaming then the Bravura.
EAX4 vs. EAX5 and new games don't even use it anymore.
Either one would suit your purposes and i doubt you would be disappointed.
Auzentech is definitely the best bang for your buck.
The Preude is a little pricey i've never seen it under $150.
I happened to buy my Forte when it was on sale cheaper then the Bravura.
All i know is that the Forte sounds great and i'm glad Wolfram23 has the Bravura.
I trust his opinion on components.
The Forte's primary advantage over other cards is its powered headphone amp (simmilar to the ASUS Essence STX and HT Omega Claro). Both the Forte and Prelude should perform about the same when using the analog outputs. As far as I know, the same feature set is supported on both cards as well...I think the only real difference is the amp on the Forte.
Did you mean the Forte?
Cause I can find the Prelude for around 100$ and the Forte doesn't go under 150$.
I live in Canada and i've never seen the Prelude under $150.
That could very well change though because it is the oldest card of the 3 we have been speaking about.
Where i live the Forte has been as cheap as $95 recently and the Bravura slightly more about $105.
The Prelude is from 2007 but has had revised editions released.
The Forte was released early 2009.
The Bravura was released late 2009 early 2010.
The Forte has the same audio processor as the Flagship Hometheatre HD card.
Like Wolfram23 said whatever one you choose it will not disappoint.
Btw i think onboard audio stinks the audio out of my 5850 sounds better imo.