And just one tip: if the Voodoo card have the firmware modified to run on Macs, it won't work on Amigas!
Do a simple test: put the board on a peecee (XP version is better for this) and hook a monitor on it. It work ok? If so, you have just a contact problem, like Wurzel said.
If winblows recognize the board, but complain it can can't use the card, you need to re-flash it. Keep it on the peecee and wait further instructions.