If you are going for hardware switching and/or multicasting with vetra products then DEFINITELY PS2.

If you are ONLY going to use software solutions (ex keyclone) then you can get the USB version. Just remember then you are slaved to xkeys software which may or may not run on future OSes. With PS2 + PS2->USB converter you need 0 software.

Also I no longer use my computers PS2 ports (so not having them is irrelevant). Instead what I do is chain keyboards and xkeys as needed and feed them into a vetra switchcasters. The output of vetras is then connected to a PS2 to USB converter which connects to a small 4 port hub (1 per computer). The hub is the ONLY thing then connecting to my computer. This way I only have 1 wire per computer going from my central vetra "spaghetti" to the computers.

Ziran