Thanks for all the info.

My inclination is to go with and Ingersoll Rand 231C (seem to be available new for about $110 shipped)for a 1/2 inch and probably a cheap one for a 3/8.

I have done the cheap route in the past on items like weed wackers and leaf blowers and in both of those casses I wound up purchaseing the better one I should probably have started with. So my logic with this is start with the higer end and then if I want a smaller tool get the cheap one there.

The Harbour Freight is tempting but they have no stores in MA (closest in NJ and NY) even including shipping it is cheap. However you can get a lower power Ingersoll Rand from Amazon for $40 - 375 ft/lbs
http://www.amazon.com/Ingersoll-Rand-IR-235-Drive-Impact-Wrench/dp/B0000224KH/sr=1-2/qid=1165067144/ref=sr_1_2/104-9365525-2617501?ie=UTF8&s=hi

I currently have sufficent shop air and in the future will be adding a lift and a large 2 stage compressor. I'm getting the impact stuff because I am going to be doing a bunch of front end and suspension work.