it would depend on how you decide to approach the problem. there are a few solutions, but i believe keyclone is the easiest and possibly the best (but i'm a bit biased... i wrote it )

for playing on one machine, check these out (pics give a good idea):

Keyclone
http://solidice.com/keyclone/index.html

Keyclone - commands & maximizer
http://solidice.com/keyclone/commands.html

Keyclone - PiP
http://solidice.com/keyclone/pip.html