Heres what you do.
Go into your game list or program list. Open up as many as you can simultaniously, and see what you can do
Next, post your computer specs, along with, if possible, your cpu temperature after running this test for 10 minutes
Heres what I got
This was with 17 of my unlimited games running
Pentium D 3.0Ghz
3GB RAM DDR2 667
You should feel the back of my Xbox 360 when only playing 1 game while on Xbox Live!