I ran up against this a few months ago. Back then there was only ONE DVI-KVM switch in the entire world. It's called the
AdderView DVI and it's made in England. There's a 2-port and 4-port version available. The only place that distributes it in the USA is
L-com.com. THis is where I bought mine. 2-port is $400:Q, 4-port is $570:Q.
I've been using mine for about three months now and it works absolutely perfect. No glitches at all and it's wonderful to get DVI quality video from both of my boxes.
There is a DVI switch available for $199 from
Dr Bott but according to the website (and from email) it only supports up to a 15" monitor. If you have a 15" monitor you could buy one of those and a regular KVM switch for you mouse/keyboard and save some money.