I bet they write drivers for all the new hardware.
As for the common onboard sound, AC97. I bet someone has written a DOS driver for that...
Instead of "betting" on it, why don't you research it and provide us with some links?
So far all I've ever seen with people trying to get PCI sound working in DOS is a whole bunch of headaches as PCI gear cannot map to low enough IRQs for DOS software.
For me, if I want good hardware support, a quick loading OS, and no GUI overhead, I use Linux. My cocktail cab uses less than 5MB total for general OS needs (2MB of that for the uncompressed kernel, and the other 3MB for the frontend and system) which leaves me buckets for ROM playing. I use a recent 2.6 kernel that supports almost every single chipset, video and sound card on the market. Gone are the days when I had to shop for specific hardware for my OS. Now I just get whatever's cheap, and I know it'll run just peachy.
Of course, insert obligatory counter-post about someone complaining Linux is "too hard" because it's not like Windows.
