Look at the label on your power supply. It may list it's output on the +12 volts. If it is over 8 amps you should be OK with a lower wattage tec like the leufkens (3dfcool.com) or other 50 watt module. The higher wattage tecs (ICE-71 etc) produce lots of heat on the hot side and tend to raise your case temperature and ,in my experience, this results in the same cpu temp as using a lower wattage TEC. This is only true with air cooling with the case on-you know like NORMAL people like to have.
What kind of CPU and mobo do you have? People here have lots of experience with different combinations and can probably tell you what heatsinks won't fit on what boards, etc.