I recenlty bought a peltier cooler for my c400 and it produces loads of heat so I opened up an unused case slot on the back near the cpu and put in a small blower fan, eg. squirel cage, and that has made the single biggest diffence in case temp, dropped the temp from 105degrees f to 96. fan is available at radio shack.
Unplug your power supply and carefully remove the fan and turn it around so it blows OUT instead of sucking air into the case.
Your fan is under 20 cfm which isn't bad for $10, but you should look into better fans for a few dollars more.
I cut a hole in the top of my case and added an intake and exhaust fan to my system to keep my case cool since I use peltiers on both of my systems also. the inlet fan is 120 Volt AC 65 cfm ($18 at Radio Shack) and the exhaust fan is 12 Volt DC 108 cfm ($16 from http://www.2coolTek.com).