I futzed for several months with DVI KVM switches, but they were more expensive and had glitches, especially at higher resolutions. Just shifted to a cheap Joytech HDMI 3-way switch, using DVI-HDMI cables (from Monoprice.com - very cheap) and now I have a DVI video switch that works perfectly. Only downside is I have to use a separate KVM to switch my mouse and keyboard. I tend not to switch back and forth constantly, so this works for me. YMMV.
Actually, this is the route I took for a while.
Then I decided to go back to a less complicated (read: all-in-one) solution. Not that an HDMI switch independent of a KVM switch is complicated by any means, but for 5 months I had trouble with that as well. There were many times I had to reboot PCs (all of them) in order to get a video signal. I spoke with reps at Monoprice about it and they informed me that I was experiencing a known compatibility issue dubbed "hdcp handshaking". So this same rep recommended a more reliable switch that does not have this particluar issue. But the more I thought about it, the more I thought it made better sense to invest in a all-in-one solution (my old KVM had died). So now I have a KVM switch that also has built-in USB switching and audio-switching so all PCs can share the same devices -- and they can do so independently of one another (1 PC might have control of the USB device(s) while another might have the audio, while yet another might actually have the focus of the KVM). It's pretty handy and creates less wire clutter while providing complete flexibility in device sharing. And thus far, it works:
IOGear 4 port KVMP Switch (model GCS1804)
It also has firmware upgrade capability. Maybe that would fix my issue...
I am just thinking a video card with an analog out (D-Sub) would probably remedy this problem. Again, I could be wrong, but I think the problem lies in the analog-to-digital conversion at the card.
I suppose I could buy a different card and if it turns out to be a solution, I can also sell the 8800GT to help make up some of the cost.