Quake 2 Evolved is a great help there: improves just about the whole experience of the game, with an improved graphics engine supporting some really impressive new effects (when you see them in Quake 2, anyway... ;)) - you can even make the HUD look like Doom 3. 8)
http://www.quake2evolved.com/files.htm
The Soundtrack for Quake 2 was really good; it fitted the game very well. It didn't hurt that it was CD audio, so you could pop the CDs in your hifi too... :D
If you've got the extra cash, and haven't got Quake 2 will all it's (official) addons, the Collectors Edition is worth it. :)
I tried Evolved - doesn't work for me, for unknown reasons. The sound is completely dead and when I start a new game (the setup screens come up ok), it just locks. I have to end task. Whereas Q2, with the patch, works fine. Barring the tiny HUD.
I'll give it another try.. Maybe I need to re-install something.