The answer is yes. Some ancient KVM switches may have trouble communicating with kvm switch windows vista and will give up. The new KVM switch windows type boxes have fully transparent usb connections back to the host computer, leaving many options in terms of connectivity from the kvm switch windows down to your servers.
If you think about it USB runs on all operating systems, and if your kvm switch windows vista box is just passing transparent USB to the server, it doesnt matter what operating system is running, as it is just communicating USB data. This as I mentioned before leaves alot of options also for attaching peripherals, such as DVD RW's, CD RW's, touchscreens, and other things.
So to answer the question yes it can be done. Chances are if it is a newer kvm then it will be able kvm switch windows vista. If you are unsure always double check with the person you are purchasing it from to make sure that it is capable of what you need it to do.