Well, I am an international student, and I mean it. I have a master in france, some grad-courses in germany and very very good undergraduate scores from a practically unknown university in eastern europe. I also worked in research but mostly in fields not related to what I really want : HEP-TH-Cosmo. Still, I know more about this field than many people that are working in it... (QCD, my first love... although a left her for string theory...)There is almost no possibility to do this at a good level in my country so I applied for some univ. in the USA. My score was not so good (little above 700) but I was accepted into a graduate program at a technical university. I got some good grades here (essentially A's some with + some with -) but I decided to take the PGRE again and to change school. I really want to have my PhD in the USA. Well, I guess I like the educational system here more than any other. Professors generally make the material seam so simple and clear, completely opposite to what I saw in other places where profs try very hard to make things as uncomprehensible as possible. My question (finally getting at it
) : what are the chances to improve my PGRE score (let's say with 200 pts)? ETS says this is unusual but for the first test I learned only 40 days or so and now I'll have 5 months. How bad will it be to have 2 scores in the report (let's say a 720 and a 920)? Are the top 20 univ. going to avoid me because of that? I'll have two recoms from USA and one from france. I can take other recoms and strong ones too but related to research in all sort of other fields except HEP-TH. I have no chance to do any new research for the next year, at least not in HEP-TH... 
and of course I'm mocked by my family and friends back home for my "passion" for HEP-TH, when I could have done so many other things for $$$ 
By the way, an unpleasant question: are there really different cut-off scores for domestic and international students?! Am I naive by asking this question?!
How long does it usually take to prepare for the PGRE?