I don't know how I ever lived without Synergy.
If any of you out there have multiple computers, whether it be a laptop and a PC, 2 PCs, or a PC and a Mac (or EVEN a plasma/LCD tv that you use in conjunction with your computer, you owe it to yourself to check out Synergy.
Instead of having 2 keyboards and mice next to or on top of one another, you could use a KVM switch. This would let you "switch" which computer the input devices are attached to. Simple Mouse/Keyboard combos cost up to $50 and ones that include video/monitor support can skyrocket up to $100.
Synergy, once installed on all the devices, will let you simply mouse over to the edge of your screen and work on the other monitor, seamlessly and fluidly. It will even share screen savers, password locks (so you only have to unlock one computer instead of both) and a universal clipboard. It's like using a dual monitor, but better, because you've got a whole other system to work with. Imagine how awesome it'd be with a PC and Mac.
The future is now!
Check it out.