Use "CPU Control"
A simple tool allow you full control over your cpu cores usages.
http://www.overclockers.ru/softnews/27878.shtml
0 - not used core for that application
1 - used core for that application
example:
1111 - this application use 4 cores
0011 - this application use 2 out of 4 cores
and so on...
enjoy
