Hmm It can't be that theres something drastically wrong with the hardware, since it runs nice and cool and stable on windows. Its an OSX problem, need to track it down though.

I'll mess around a bit with different configurations (kernels/AppleACPIPlatform.kext etc)

See whats going on on Activity Monitor.

I'll do that later, too late now.

Also I'm not sure if I should open my computer, itll void the warranty...about half of the 3 year warranty left..

Fan currently at 2220RPM according to PC Wizard 2008

Also I lack money for new hardware and such