Hey guys, first time posting here, hoping to get some useful instruction

. As it stands, I just upgraded my computer from an Intel Pentium Dual-core E2200 to an Intel Core 2 Quad Q8200. It sounded like a great idea, but now I'm having a problem.
It starts up and runs in windows fine, but I noticed that although the System Properties and the Device Manager seem to recognize all cores and that it is Quad-core, the Task Manager and msconfig show only two cores.
Now, I may just be stupid and confused about something but the task manager shows that the two cores seem to get to 100% usage pretty easily, like my old CPU did, which was unexpected if it is working right. In addition, it seems to be running hot, according to Speedfan at least.
I don't know what to do to get it to recognize all cores.
My computer is an Acer 5640 that I bought standard with 4GB RAM, Pentium Dual-core CPU, and all that jazz. If you need more information be sure to let me know. Also, if it applies, I have an Nvidia 8500GT that I upgraded to a while ago also.