It's easy to cool a tower case.
http://www.tigerdirect.com/ has 100+ case fans.
Front 5.25 - micro single and dual fans, with or without ducts that direct the flow into the case.
Rear expansion slot - exhaust fans that occupy these slots are typically cyclone fans, with an intake spout. Something new is a twin fan with extending ducts similiar to the front fan kit mentioned above.
Special note: read the specifications. Pay heed to the .dbA noise ratings. Read the "reviews", as these are really excellent on the fans. Buy fans that have real ball bearings. Almost twice the life potential (50,0000 hrs), as compared to sleeve bearings (30,000 hrs) when possible.
Do NOT buy the Radio Shack 273-243 Brushless 12vDC fan. It will lockup, and you'll never know it.
