I just got my PowerPro 256 and its great.
Here are my two contributions to other beginners like me. These are links to EXTREMELY HELPFUL handbooks that are free online, regarding welding:
Miller's TIG HANDBOOK
http://www.millerwelds.com/resources/TIGhandbook/
and also
CK Worldwide welding "specs" (like the handbook above but with even MORE detailed info)
http://www.ckworldwide.com/technical_specs.pdf