Now that would be fine except that you can have only one instance of TCP\IP installed, so dont think about accesing more thatn one network.
I'm not sure what you mean by more than one instance of tcp/ip, but I have had no trouble converting an XP machine into a multihomed box, as long as you're using static addressing.

My opinion of XP, a cartoon artist redesigned 2k and made it ten times more obnoxious.