Help ATI9800 A-I-W in Acorp Dual-P3 - drivers will not load

[RRLedford]

I own (2) Acorp 6A815EPD Dual P3 boards that replaced failed BP6's.

Recently wanted to upgrade video from GF2-MX400 level to GF-FX 5700+ or ATI-9700+ on both.
This has turned into VIDEO UPGRADE HELL!
I was getting deals from NewEgg on their "refurbished" vid cards.
First effort was an $140 FX5700Ultra from PNY - the ACORP WinXp-Pro build was a Ghosted clone from my first Acorp with an Aopen GF-MX400/64M card. I downloaded in advance the latest Nvidia drivers and latest DX9 too.
1st FX5700 boot of WinXP would only load generic VGA driver but still in 1024 mode with high colors. However DXdiag.exe showed no accellerators were loaded!!
After removing/reinstalling, disabling/enabling, downgrading/upgrading dozens of times - I was able to get a few boots where the advanced DX9 drivers actually loaded. BUT, every re-boot would go back to generic VGA with no DX9 support enabled..
Finally got NewEgg to take it back for credit & stuck an old FX-5200 card in the system. Well, what do I find - same problem, not able to load DX9 drivers. I take the card to my older ACORP system and install it there, only to find the same problem. Now I'm thinking Nvida FX series just not compatinle with ACORP.
So, I get a deal on an ATI 9800 A-I-W card for $198 thinking it will solve my ACORP video problem. Does exact same thing - drivers load once in maybe 2Hrs worth of screwing with uninstall/reinstall & then dead again after next boot. Now I'm very down on ACORP - kids can't play games.
Then WinXp crashes on the older ACORP system & I have to do a full reinstall. Surprise - now my FX5200 card loads all DX9 accellerators on every boot!
So, the question is - must I do a full WinXP reinstall to get the ATI9800 card to work? Or, can I get my machette out and head for the depths of the Registry to solve this problem?