Combining NICs for speed

I am trying to get two or more NICs in my Win2k server to combine under one IP address and share the I/O on my server. I have seen it done, but can’t for the life of me figure out how to do it. I remember that both NICs got unique addresses originally and then they were combined to answer calls and coordinate as one NIC. Sped the network up considerably on the Exchange Server.
Any help?