any slim fan will work, but a Farnell or Jameco part number would be nice...

Here is a Mouser part number for an ADDA 40x6 12v. They also carry 40x6 5v further down the page...

http://www.mouser.com/index.cfm?handler=displayproduct&&lstdispproductid=496915

BTW, I connected to the header using a drive jumper. Pulled off the jumper's plastic case, soldered the wire on, replaced the case and now the jumper slides snugly onto one of the header pins.