actually you should only be able to see two computers. the two on the right of the picture (personal computer, and server (smaller one)). my gaming computer is in the car. so in reality, i have 3 towers, and two laptops (although one's too slow to hardly even use)
1) primary computer (what i'm using right now)
2) server (cables lying on top of it are what my gaming computer plugs into. gaming computer sits on top of server)
3) primary stereo
4) KVM switch (primary, server, and gaming computer)
5) secondary stereo (sometimes listen to both on... as you can see i have a couple of speakers, surround)
6) printer (not working at the moment)
7) nifty little thing i built... light switches, but with the speakers wired through them. since my primary stereo isn't surround capable, i've got 6 speakers. two in front of me, two further on each side (like the one directly next to the stereo), and then two far on each side (the other two corners of my room). i can turn off each speaker with this little 'box'. not too practical, but pretty neat
8) subwoofer for secondary stereo
curious what you thought was the 3rd and 4th PC in the picture