Windows Server 2003 and 3 NIC's?

I have a Windows Server 2003 that is my company VPN server. Two NIC cards, one for our private company network and one for the public side...works great. Here's my question: I have a network storage drive (Iomega) that I dont want my users to have access to, so instead of hanging it on the company network I was thinking I could install a third NIC, make a crossover cable, and tada everything would be right with the world. When I installed my third NIC, my machine was taking forrrrrever to boot because it was trying to use that NIC to access the domain. It would eventually boot, but it had issues. I disable the NIC, and all would work again. OK, so actually this is my question: How can I isolate that third NIC so my machine will not try to boot with it but I can still use it for my Iomega network drive? The Iomega has an IP, so the NIC would have to have an IP to communicate with it. Any ideas?