My Dell Inspiron E1705 is about 15 months old now, and recently I've noticed absolutely appalling framerates while playing my favourite waste of time. Where I used to be enjoying 30-80fps, depending on my graphics settings, I'd found myself gradually lowering the settings and resolution down the the bare minimum and still only getting about 5-15fps. That's right, 5fps - try playing AB at that speed!
I figured it must be the GPU or the CPU protecting itself from overheating because I could feel the heat radiating out of the keyboard especially from the top right by the Page Up/Page Down keys, and the superb I8kFanGUI was reporting CPU temperatures in the 60s and GPU temps in the 80s.
So, with the help of Dell's online maintenance manual, a screwdriver and a vacuum cleaner, I ripped my notebook apart and removed a huge buildup of dust that was clogging both the CPU and GPU heatsinks. Removing the fans and sucking the dust out of the heat exchangers was enough to clear the blockages, I didn't have to remove the cooling assemblies themselves.
Since then, I've been getting a solid 85fps at WoW's lowest settings and 20-30fps at 1650x1080 with all the settings maxed out. The CPUs are a balmy 53 degrees and the GPU is a temperate 60.