Seen the recent review of the CoolFX water cooling unit? Seems to me that the existing air cooling vents the hot air out of the case through the card slot. However the CoolFX heat exchanger vents the hot air into the case (specially down towards the harddisk).
I wonder what the internal case temps could rise to after a while of use. Not to mention the thermal stress on the harddisks with the hot air flowing over them.
it all depends on your system, if you have enough case fans this would be no problem, the biggest reason to buy a cooler like this would be noise, the FXs are very very loud. If you need a good case for cheap xtreme gear is selling the equiv. of the antec sx-1030s for 35 bucks plus shipping, I paid 80 for mine! Get them while they are still selling them. They are very nice cases that will vent that hot air right out with enough fans.
Treat your body like a $600 car. God didn't intend it to last so use it. Run it into the ground!