[SSGoku]

I find myself in a situation where I need a PC to run a specific M$ Windows app for work. Fortunately, my brother is trying to get rid of his old PC. He has a 600 Mhz P3, 256 MB, 32 MB Riva TNT2 video card running Win XP Pro. A free PC or buy Virtual PC? Well I decided to go with the free PC and try it out.
The problem is that my brothers 17 inch CRT is a piece of #%$. Its ready for the garbage. My Mac has a Samsung 193P 19 LCD attached to it via DVI cable.
My dilemma: Should I get a KVM switch to share the LCD? Or should I get a new monitor?
My Mac is the main machine. Ill be using the PC for a few hours a week at most. A KVM is certainly the cheaper solution; however, the PC is a PS/2 computer and my Mac has a USB mouse & keyboard. Since my Mac is the main machine, Id prefer to use USB keyboard & mouse.
A new monitor solves the problem, but its the more expensive solution.
Any advice?