BlackBox ServSwitch series is pretty good, but you're going to pay through the nose. Problem is, with KVM or V switches, you really get what you pay for and the sub-$200 ones suck at high resolutions.
How often do you switch? A ghetto solution might be to run a 36" VGA extension cable to the front of your desk and simply plug/unplug whichever one you want.
Pentium IV 2.4C Northwood- M0 stepping @ 3.2GHz HT
Air Cooled w/ SP-94 heatpipe & 92mm Vantex Tornado at 45C
4x256=1gb dual-channel 2-3-3-6 OCZ PC800DRAM @ 890MHz 3-4-4-8
MSI Neo2-PLS w/I865PE & SATA @ 4x267=1068MHz
BFG GeForceFX 5900@485/967MHz = 6284 3DMark2003s; dual-head 21" CRT & 19" LCD