Multiple Network Connections

I have a Windows 98 laptop user who sits on out NT network. For various reasons the network setup is using a static TCPIP address and a default gateway is entered. However, this user needs to visit another site and wants to connect to their network(completely seperate). Again it is a NT network but this time they use DHCP to provide TCPIP addresses. Also the Domain names are very different. Is there a way that I can set up both domains on his laptop in order that he does not have to change the network settings in the control panel every time he visits the other site. I guess that with another network card in his machine we could overcome the TCPIP addressing issue but what about the Domain issue?