You're on the right track with the RAM, 2GB is good enough for running 3 clients. I would guess the rest of your system should be able to handle 3 as well if you keep it confined to a single monitor, though I'm not 100% sure what level that video card is at. I've successfully run 3 with a computer that was 3 and a half years old (though it was top of the line then), so you should be OK. Have a look at all the stickys in the beginner's forum for help getting set up multi boxing on a single machine, there's tons of great info there.