Where is the best place to find a cheap flight to usa?

Fab info Ricki! Maybe you should write a "How to" for the Just Do It board. 

Excellent idea! 

Yes Ricki - you really should!

If it helps, I know that Delta's hubs are Atlanta, Salt Lake City, and Cincinnati (unless the last two changed after the bankruptcy, but I don't think so).  The main one is Atlanta as Ricki indicated.

BA flies straight through from Heathrow to Dulles.

They also fly from Gatwick to Atlanta direct.  Delta does the same, and also has direct flights from Manchester (UK) and Edinburgh to Atlanta.  Good starting point if you're heading into a smaller Southern city, like Ricki suggested with Nashville...

MaxiJet flies cheaply to D.C., Las Vegas, and either New York or L.A., I believe, and the service is great.

You gave a good suggestion. I spent time checking them out and it looks like a real good find.
To be picky...It is spelt Maxjet (no i in the name).
From what I can figure out it is a US carrier.
Imagine it is a one class airline having only business class.
Thank you again for the lead.
Now someone also said Jetblue is starting service from Las Vegas to Belfast and I was wondering how I could find out more. Their web don't say notin'.