for detailed information on flying in the US, incl. the issues of visa, do read the accounts of Destinationsky and Backpacker, and mine. . Whatever school you choose make sure that they are properly licenced, fully insured and are open and square in their pricing structure.
Destinationsky
http://www.pprune.org/private-flying...nest-view.html
Backpacker
http://www.pprune.org/private-flying...hlight=Florida
XLC
http://www.pprune.org/private-flying...ch-2010-a.html