Right click on My Computer> choose properties and look at the General tab to see what version of Windows you are using.
You need to get that computer out of the cubby hole.
From the differences in the temps I would guess that either the heat sink on your CPU is really dirty, or there is something wrong with the fan.
See what happens to the temps once you have the case out of that desk.
You probably need to disconnect the wires in order to pull it out. That would be a good time to clean out the insides.
Go to a computer or office supply store and buy some canned air and use it to blow out the dust/dirt. Be sure to also blow out the power supply from both ends too.
DO NOT use a vacuum cleaner. It will be messy so you may want to find a better place to perform the blowing out.
After that, make sure none of the cables came loose.
When you connect everything back up leave the side of the case off so you can watch the fans to see if they are all spinning.