Just put the PC outside
EDIT: Or jam the PC in the window!
Tempting as that is, I'm not sure if exposing my £1800 pride and joy to the elements is the best way to go
Finished moving stuff around and I'm fairly happy I've done as much as I can to optimise the cooling to fan noise ratio for now.
When it's sunny, I can keep the gaming rig under 80C with the fans slightly under half speed (still slightly noisy with the Triebwerks but bearable). I can keep the other i7 rig under 80C with the fans on minimum setting which, as it's under the desk, is unnoticeable with the gaming rig going. I really need to change the radiator in the gaming rig for one that can work with lower noise fans but that'll have to wait until I have money.
It's damp and cloudy today and not terribly warm so both rigs on lowest fan speeds - nice and quiet.
I've also done a bit of shuffling around. I've taken the 8800GTX out of the little mATX machine and put it in the bedroom machine. I've retired the mATX rig for now.
It's now much more comfortable in the PC room