Usually use a combination of the 5.25 bay cooler and the PCI blower below, can be hard getting a PCI blower which is full height into a micro atx 1/2 height case, always get them in though.

http://www.maplin.co.uk/Module.aspx?...20fan&doy=13m2

The 5.25 bay unit with 3 fans shifts a LOT of air, the pci blowers shift about 1/2 of what the 5.25 unit does.