3com 11 a/b/g wireless pci adapter configuration problem

[jjtbt]

I have a 3COM 11 a/b/g wireless PCI adapter that I am trying to install in some older Windows 98 PC's. In one PC it installed successfully right off with no problems. In 2 other PC's after I install it and turn the PC on, the video never initializes. In other words, the PC powers on, but the monitor never kicks on. I've tried different slots, different video cards (even different video cards using agp, pci, isa), and in the BIOS I've tried manually setting the irq that each PCI slot is using. Also, in the BIOS, I've disabled all other on-board integrated devices (com ports, parallel ports, etc.). There are no other cards in these PC's except the NIC and the video card. One of the motherboards is an Aopen AX5T and the PC's are all 1998, 1999 purchased. I was reading that PCI slots have different "voltages"...can this be the culprit, or does anyone have a suggestion?