[mickmate]

You will need about an amp per 10 thousandth of the thickness you're cutting. If you want to cut 1/2" you'll need 50 amps. 1" needs about 100 amps.Stick with a good brand for parts serviceability reliability etc. The two best companies are Hypertherm and Thermal Dynamics in my opinion. Too much power is easy to dial down, if you need to cut something thicker you'll have the power when you need it. I have run a Thermal Dynamics machine Pak 55R that had a hand torch that will cut 5.5" thick. People don't stop to chat when you have that much power in your hands. You'll find no end to the uses for them. I've seen some good deals on new warranted Hypertherm's on e-bay.
Good luck with it.