More thoughts. did you run the compatablity program from the xp cd first ?
It would have told you what was going to work and what was not.
Try uninstalling xp and start again useing the cd to check your system.
XP has a ton of generic drivers preloaded just for the purpose of upgradeing.
You say it didn't see your video card but it must of or you would be looking at a black
screen. it used a generic driver. you need to get the oem driver from the manufacturer.
Then you should be ok. most older nic cards are plug n play and xp should have
no problem with them. as far as the sound card, thats another thing all together.
Sound cards need origanl oem drivers most of the time.
Don't give up. it may take some work but you should be able to getxp to run decent.
Increase your system memory to at least 128 meg, 256 if possible.