Question : Software KVM Solution

I am trying to find an alternative to a KVM Switch hardware solution, basically a free solution.  I heard about software solution &Ultra VNC with SC addon& I did some reading, and I suppose I could figure it out without screwing up my computers.  Before I go messing around with my computers I thought Id come over to Experts Exchange and ask.
I have a Dell Desktop running Windows XP (SP2) and an HP Laptop running Windows Vista.  I want to use the Dell monitor, Wireless Keyboard/Mouse to control both computers.  
The main reason is where I develop questions& PC Gamming!  One of the first questions I have& is a software solution viable as far as the graphics/video resolution?
Im a bit confused as to which software solution to use and I dont know if there is any software solution that will suit my needs.
Anyone have some advice?

Answer : Software KVM Solution

The monitor is the only real issue here. If you had an additional monitor you could use the same keyboard and mouse with the Synergy and control both machines that way. That is how I user the same Bluetooth keyboard and mouse on my laptop (Debian Linux) and desktop (Vista).

Synergy: http://synergy2.sourceforge.net/

I have yet to come across a "Software" KVM so if a hardware KVM is out of the question then I don't really know if you will find exactly what you are looking for.