The American Embassy is a good place to start! If you're British then good luck, it is very hard to emigrate to the US. Here is a link from the American Embassy website http://www.usembassy.org.uk/cons_new/visa/iv/i ndex.html
Good luck lou. Friend of mine owns his own company, is technically qualified in an unsual but applicable specialty and has an American wife and has just been turned down for a VISA !
It is very difficult to gain entry to the US to live there. Most people end up buying a business but there are lots of hurdles to get over. We have friends over there at the momnet. They run a management company in Florida. They have a visa for 5 years but don't know if they will get an extension even though their business is doing well. Good luck!