there's two main things to look at on a peltier.
The first is the delta possible
the second is the power of the peltier.
you need about double the heat output of a cu to coll it effectively.
If your peltier is not powerful enough, then the cold side can't take away heat from the cpu fast enough - eg, say you attach a 90W pelt to a 110W cpu - you're not taking more heat away from the cpu, and the cpu can overheat, and burn.
When you use too hot a cpu, the peltier actually acts as an INSULATOR
it's messy - you need to smear your socket and around it with dielectric, coat your electricals in waterproof coating - fingernail polish or paint or something. silicone etc.
guesswork - your cpu is 110 w - but you're going to run that stock if using a peltier? NO! you're going to overclock. so multiply the wattage by new speed/stocl speed and by new voltage/old voltage for an approximate change in the wattage. e.g. overclocking a 3700+ at 80W from 2.2 to 2.9GHz and passing 1.5V instead of 1.35
watts output = 80*(2.9/2.2)*(1.5/1.35) = 117watts.
so instead of a 160W peltier, you're looking at 230watts.
They DO have 224 watt pelts, but you don't wanna run electrical components at their max and expect them to last. There's 400 watt peltiers too. NOW the problem is getting power. For a 12 V pelt, you need 33 amps, 35 amps is hard to come by. There's a few power supplies that can take that. splice the middle green wire to your main psu and a black one near it (all black is ground) and when the main psu starts, so would the secondary. You can get a specialized psu for it, but they're expensive.
The biggest problem now - cooling the blasted thing. You're NOT cooling your cpu, you're NOT cooling the peltier. You're cooling BOTH the cpu and peltier. If you oc'ed a prescott, then it's possible you're talkig about almsot 200watt's of cpu AND a 400 watt pelt for 600 watts. you will need water cooling, and GOOD water cooling at this point.
Now look at the cost - you're talking top end watercooling - $300 to $400, a high end pelt, an incredible psu, and loads of electrical power. Take a look at vapochill. When conroe comes around, peltiers would be much much more viable.