Hello and welcome to the forum.
I would check for any dust around the CPU or just in the case in genreally and use compress air to clean it out. Also check that the fan does come on when it should come on. You should no let the computer get too hot as it can damge something inside.
You can also download speedfan
http://www.almico.com/sfdownload.php and use that to keep track of the tempature of the computer.
and yes this is more in the wrong area, more of the CPU section would be better i think, but just check that the fans are clean and still spin when they are suppose to.