Ok. From what I can see, problem fixed.
Behind the actual fan there was like a sort of turbine looking thing, it was absolutely chockas with dust, I was spluttering and coughing getting it out! I couldn't believe the amount, I had to get out the 5 million candle power torch to see it properly it was so dark.
Well eventually I cleaned it out, and launched a couple of my games, checked out the frame rates and it was sitting at around 50-60!
I'm not sure what I could expect with the setup i've got, but it's silky smooth!
If any other problems come up, i'll be sure to come straight to this forum, NOT the computer guy down the round who ripped me off twice (vegas 7, and an ATI GPU).
My sincerest thanks to the community for the help, it's much appreciated.