the white slots are the PCI-32Bit slots exellent for PCI 3dfx cards

even modernday PC's of today have them like my ASUS A8R32 MVP Deluxe ATi RD580 CrossFire Xpress 3200 Motherboard does


The VoodooMAC 5500 PCI is in the PCI-32Bit slot above my Sapphire X1900 XTX

Your PC has these white PCI-32Bit slots as well, so if your Voodoo3 is a PCI one you're in great hands, just remove your modem card and place in that Voodoo3. 8)
What Operating System are you running at the moment?
If it's Windows 98SE I'd say get these:
AmigaMerlin V2.9 Win9x Driver Latest ReleaseIf it's Win2KPro/XP Pro Get these

:
AmigaSport V3.0 WinXP/Win2K Latest ReleaseHeh That Dual Pentium3EB 1Ghz system is still in service at a good friends place, it's running 24/7 as his main server for about 4 years without a crash

, he put Windows 2000 Server on it