Normally the discs and such you get from manufacturers are geared towards windoze. Open Source or even closed source drivers are usually done by someone else, however it's becoming more and more common to be in house work (which is great news). So it's likely that disc is specific to windoze, and really it probably has nothing beneficial as far as drivers are concerned anyway as most of your hardware support is in the kernel.
As for your sound:
Mandrake runs ALSA by default. Your card should be sufficiently driven, you might just want to see if there is something muting it by using alsamixer as root. If you don't have that utility installed, search your install discs, or use urpmi and type:
I believe that is the application/package containing alsamixer. To launch alsamixer, login as root, open up a terminal and type:
If it is installed, that will launch the application (it's command line but ncurses) and you can adjust your sound much better with that.