I would put it at the back, or else a big one in the left side panel or in the bottom panel with the case standing on feet. I wouldn't put a fan right on the radiator, but have one or more fans drawing air into the case (through a dust-filter). Close up any other holes in the case. The air will leave through the radiator but you won't get the extra noise from the fan blades being next to an obstruction, and also the whole case will be acting as a plenum chamber or shroud for the fan.
Sure... where does heat diappear thean...
Partly through the PSU... Keep the PSU warm and you just added a little extra noise in your system. I say keep it out of the case. I got some mounting idea I am going to try tonight... will let you guys know tomorrow (or day after depending on how fast I finish them).