While I won't claim to have had trouble free installs. I have 2 systems running XP with GeForce 2 MX200 video cards.
1. Have you downloaded the critical and compatability updates from Microsoft?
2. Do you have the latest drivers installed for the chipset on the EPOX motherboard?
3. How about the XP update for the SoundBlaster?
4. Don't discount the fact that loosening the card improves the operation.
I have had to modify many cases in order to get video cards to fully seat in AGP slots.
Even one end of the card being 1/32" up can cause strange sysmptoms and failures.
Look closely at how the card fits in the slot at each end.
Remove the bracket from the card, and see if it seats in further.
And, if the system works better.
If removeing the bracket fixes things, then you either need to modify the bracket so that the board sits down a little deeper, or space the mother-board up a little higher.
I have one mother board that gave me fits after 3 months of running. I finally tracked it down to corroded pins in the AGP socket.
I have 1 case, where the supplied stand-offs place the mother-board 1/8" too low for an AGP card to seat properly.
5. Double-check your AGP related BIOS settings.
I have the AGP apperature on both of my systems set to 256MB.
Everything else is set to auto or default.
I was advised by Microsoft Tech Support to set the Plug and Play operating System Switch to NO!
6. Try your plug-in cards in different slots.
You may have changed the video IRQ in BIOS settings, but XP will over-ride those settings, and assign IRQs as it decides is best.
The only option, is to move cards to different slots.
I would also disable any mother-board resources that you are not using. (COMM, I/R)
Chas