well after folding cables and everything, I got the Voodoo5 5500 PCI 64MB Rev.A1 2900 in PCI Slot4 of my MSI MS9130 K8T Master2-FAR from the dual OpteronDP 244 sys.

I installed the card via divice manager and installed the card manually, and rebooted, so here are my results!

Card 1 ASUS AX800XT PE CRT-Out
Card 2 ASUS AX800XT PE DVI-Out
Card 3 AmigamerlinXP 3.1 R11 for 3dfx Voodoo5 5500 PCI

OS: WindowsXP Professional USA + SP2.
ATi driver Omega Catalyst 5.4
3dfx driver AmigamerlinXP 3.1 R11

here some pics!:

The Machine is FIREFOX, and he will recieve a V5 5500 PCI in PCI Slot 4, yes it wasn't an easy task, but hey it came out , just :-X .
http://www.3dfx.ch/gallery/albums/album93/DSC00519.thumb.jpg

The Dual OpteronDP 244's fired up and ready for 3dfx Voodoo5 5500 PCI placing.
http://www.3dfx.ch/gallery/albums/album93/Opterons.thumb.jpg

ASUS AX800XT PE AGP sellected, 3 Screens visible :)
http://www.3dfx.ch/gallery/albums/album93/ASUS_AX800XT_PE_AGP_sellected_3creens_visible.thumb.jpg

Voodoo5 5500 PCI USA sellected, 3creens visible :), it works :)
http://www.3dfx.ch/gallery/albums/album93/Voodoo5_5500_PCI_USA_on_Dual_OpteronDP_244.thumb.jpg

Voodoo5 5500 PCI USA detection, and Device manager spots all three display adapters neatly
http://www.3dfx.ch/gallery/albums/album93/Voodoo5_5500_PCI_USA_detection.thumb.jpg