Mac + PC Using A Single Monitor

I have to think there are some smart, technically inclined people that visit the site every once in a while. I would appreciate any help or feedback you can give me in setting up a PC that will co-exist with my current Mac setup. I just want to get a PC box and some sort of switchbox that allows me to utilize my Cinema Display, mouse and keyboard. There’s gotta be some way to just switch back and forth, right? And please, spare me the platform-flaming comments.