If you find yourself with a second computer but want to continue using your original PC, too, but don't relish the associated double clutter, Belkin's 2-Port KVM (Keyboard, Video, Mouse) Switch (bundled w/ cables) allows you to operate two PCs through a single set of interface devices.
Drawing power from the PS/2 keyboard port, the diminutive splitter unit will fool both computers into thinking they are each connected to their own set of peripherals. It allows the user to switch active control from one to the other with the flick of a switch or hotkey, reducing clutter, redundancy and the expense associated with those "monitor not included" deals, because you can, after all, use your old monitor with you new PC--and the old one, too.