Avi Dardik has a quick guide on how to set up a secondary PC using VNC (for multi-platform support) to act like a KVM switch and allow you to switch between active full-screen sessions on your host machine and a client machine at the tap of a hot-key. Although many may argue that using VNC software for this purpose is a pretty ugly hack, the reality is that this scenario is extremely common, and very fast on a local network.

Remote Desktop is simply faster and more efficient between Windows PCs that there's no reason not to. That is, of course, if you have XP Pro or a flavor of Windows Server for your "client" machine. XP Home won't allow you to make a Remote Desktop connection to it unprompted.