problem with dual-monitor with a ATI Mach64 CT PCI

I've had this exact same problem for about a year and a half now.  Sorry to say I can't find a solution that's permanant.   I have a precision 330 with the wildcat AGP card.  I was running windows 2000 when I picked up a PNY nvidia GeForce2 PCI card.  I added that and it worked fine untill I upgraded to winXP pro.  At that point the nvidia card just refused to start.  Always giving me an error code 10.  I tried re-installing the drivers on both cards.  Looking for updates to XP, reseating the cards, moving the PCI card to a different slot, changing the primary card in my bios.  Etc etc.   Occasionally I would get it to start up with both cards but it was completely unpredictable.  After a while (I think shortly after one windows update I isntalled) it just started working right and stayed that way for about 9 months.  Then bam....one day it just krapped out on me.  Then it started running on one card or the other unpredictably (meaning one time I boot and it's on one card, the next time it's on the other).   The odd part is that when it's on the AGP card, it gives me an error code 10 with the PCI card.  But when it's running on the PCI card it says that the AGP card is fine.   In the device manager it says my agp card is working properly, but it doesn't show it in the video settings or provide the option to extend my desktop onto it.   Very frustrating.   I had it running right last week but unfortunately had to reboot for an installation and now I'm back to one monitor.   Dell Tech support, and MS tech support were both useless.  I did discover that it sometimes works after going into safe mode and running system restore (even though I always get a message that system restore was unable to restore my system and nothing has been changed).   Perhaps that's just chance and superstition, but whatever.  At this point I'm ready to dance on my head and wave a chicken's foot in the air if someone tells me it'll make this thing work.

Scott