VMware and MapleStory: How To

I've been trying to get VMware to work running two MapleStory clients, but everytime I have MapleStory running on the host computer, the virtual computer crashes. I've tried switching up the RAM and amount of disk memory is has, but nothing works. Any way to fix this?

This happened in a friend of mine's PC that has an AMD Sempron Processor, and a NVIDIA GeForce FX 5200. I guess this method requires a heavy setup and won't simply work in every computer out there. Can you post your PC specs so I can properly help you?