ive done it before, it helps if you have a router, that way you dont have to worry about ip's, for the server machien, make sure u set it to a custom ip, eg 192.168.100.153, that way it wont take another ip, then make sure it has Xp PROFESSTIONAL, Home will nto work as a remote desktop host. Then right click on my computer go to properties, then click on remote tab, then check the checkbox that allows people to connect. then on the workstation machine, run remote desktop, (start all prog, accessories, connectivity, remote desktop) then type the ip of the server, then click connect. you should be prompted with a login screen.
yes, i know this was confusing, if u didnt understand any part, just ask.
if you dotn want to do that, go with the good ol' KVM Switch.