You will have to look in the Xorg documentation for specifics on your card, such as if it has a certain driver for the ATI card. This website may be of help.
http://www.freedesktop.org/~xorg/X11R6.8.0/doc/ati.html
You may need to edit the xorg.conf file to enable some options.
For the soundcard, if alsa is installed, then you should run the
alsaconf program for soundcard selection. Then run
alsamixer for adjusting the various levels.