As a non US citizen, an FAA licence is of extremely limited value. Expat jobs elsewhere in the world that accept FAA licences are generally for experienced pilots (and 500 hours is a drop in the ocean in that context). Unless you can get a Green Card (have a search for earlier discussions) you will not get proper employment in the USA, where the airline pilot market is, in any case, far worse than in UK and Europe thanks to the ongoing post-9/11 troubles of an industry which is largely bankrupt (though protected from creditors by Chapter 11 legislation) and thus unable to expand. Several thousand US commercial pilots are stll furloughed (laid off) from these airlines, and they're in the queue ahead of you.
It is possible to take the FAA licence and then convert it to JAA, but this isn't an easy or cheap option. Again, it's been discussed here many times before.
In summary, there are no short cuts in this business. If you have US residency and work rights (the 'Green Card'), then the FAA licence may be worthwhile (but remember what I said about the US pilot employment market). Otherwise, it's probably a waste of time.
Scroggs