Why does a NIC slow a pc at startup?

When I add a NIC to my Micron Millennia 350, Windows takes an extra 5-10 minutes to startup. The system just sits at a black screen for these extra minutes and all of a sudden the harddrive starts processing again and the startup process finishes.

It doesn’t matter which PCI slot or the type/brand of NIC. I’ve tried 3com, Linksys, Netgear — ethernet and phoneline — with all the same results. It seems to work the same with all 3 Windows (95, 98, Me). We have 3 pcs exactly the same. All act the same way.

I have no idea what else to try. Do I need to change BIOS settings — if so, which ones?