I have been fortunate to not be in this sort of situation, but if I was, I would really examine both programs and see what you get out of it. I think you are talking about MITES and MITES is more of a summer program to take classes, although it does increase your chance of acceptance to MIT tremendously if you go. This local research opportunity isn't MIT, but you get to work on whatever you would like (I don't know much about this program so I might be wrong). It seems like to me, you simply want a fun, non-boring way to spend your summer and both of these programs offer that. I will tell you that MITES will probably not tell you your decision early (but go ahead and call just to try). All the people above me have listed out your SAT and PSAT scores (congrats on those by the way), but realize acceptance to MITES is much more dependent on those teacher recs and short essays you wrote. I have no doubt you are an exceptional applicant to the MITES program, which is why I can see you are having this predicament. I know MITES also offers a one-week program at MIT as well as an on line school type option (in addition to the actual MITES program). If you do commit to this research program, and you get into MITES, see if it is possible to "downgrade" to the one-week program or on line school (I would call the MITES office about that question asap). It seems like you could do both programs if you opted to do the alternatives to MITES.
After all this rambling on my part, I also suggest you go to this site called College Confidential and find the past MITES threads. Look at the stats of the people that got in and try to predict how your decision might be. If you want to take the gamble on MITES, make sure you know what you want to do over the summer if you don't get in.
Also, on the research program, is it possible to accept admission and then later deny it? Could you somehow magically have an "emergency" come up after being admitted to MITES and not attend the research program? :P
Whatever you pick between these two, and whatever happens, just know that you made the right choice because say if you did the research program and found out you made MITES, research is something MITES doesn't offer so you are at an advantage in those terms.
I wish you the best of luck in this decision, and once again, do not let what you think may have been a bad choice to affect your whole summer or any other part of your life. Both of these programs are great, and if you end up not going to either, there are plenty of things you can do around the metroplex that involve math and science. Maybe this could be your backup program:
http://nanotech.utdallas.edu/community/ ... ation.html