My slave machine on which I run 4 instances is a E2180 CPU @ 2.8GHz w/ 2GB of RAM and a 256MB GeForce 6600LE (this is a particularly slow 6600 as it has no fan) coupled to a 22" wide display. Turn all settings down to low, make sure FSAA is disabled. Runs 20FPS min except in busy areas. Not ideal but certainly usable.