Well first off i'd advice you to upgrade your RAM if you're gonna be running virtual machines.
That said i set VMWare to use both cores (i work a lot in windows) then i turn off 3D acceleration since its useless either way with the GMA X3100. I have 4GB of RAM so i dedicated 1GB to the virtual machine.
Thats pretty much it everything else is set to standard. Oh i also pointed the 'shared folders' to my documents folder so i can drag and drop across both platforms