Heh. We should put up a MacGyver PC repair tips&tricks section...
Although I've only thus far replaced my CPU fan with one size bigger - it didn't really have appropriate holes for screws, so I made them. Also, the heat sink had these edges on the sides that were a tad bit too shallow... but they bent nicely outwards, and the new fan sat on it's place rather fine after that.
Also, I happened to have a grille on the PC's detachable side panel about on where the CPU heatsink was on the MOBO, so I cut a 1.5 litre Sprite bottle, duct taped it to the fan and added some duct tape to the other end so that the grilled side panel would meet it. So now my CPU fan sucks in fresh room temperatured air through the grille and the air duct, which means that my CPU heatsink gets room temperature air instead of case temperature air.
Zalman's VGA coolers seem to be rather fine, I've got one (namely VF-900 Cu) for my XFX GF7600GT (which is factory overclocked to 650/1600 MHz for core/memory), and it sometimes goes over 50 degrees celcius under heavy load. I've never seen it go past 60 degrees Celcius with this heatsink installed.