The sound chip is correctly probed by RH 7.3 and you should have no problems
with it, except with Real Player as detailed below.
Early Linux-compatible versions of the player are available at
http://proforma.real.com/real/player/blackjack.html
You may have trouble with the sound not working, in which case set View >Preferences > Performance > Audio Driver Options to enable ESD support, and run esd:
$ esd
This allows multiple devices to access the sound card. As esd will upset some other applications (notably xine!) you will have to kill the esd process after using Realplayer....