Don't take me to task on this nor am I definate but the Compaq Presario models usually come with a minimal 3D capable card and a metsa-metsa sound card. And quite often the systme memory is shared between running apps and for the vid card.
I added a Voodoo II to my brother in laws system and it help ALOT.
You might want to run DX7A's DXDiag and check out what drivers you have for the vid and sound card. That will help you determine the actual manufacturer for those items.
Also what are the system specs? How much memort do you have? 32, 64 or more MB? AGP port? All that fun stuff.
Once you post what you have then folks can offer advice on what they recommend you might want to upgrade.
---Westy