I would like to contrast Loric's advice with something USC DGS Mark Schroeder said on a Leiter thread awhile back (comment #56 at http://leiterreports.typepad.com/blog/2011/03/are-some-schools-using-undisclosed-gre-cut-offs-in-admissions-decisions.html):
"This year at USC we had just over 130 applications. Of those, no more than five were weak enough to be "not serious candidates". For the rest, I had to spend time reading every letter carefully, reading the personal statement and comparing to the applicant's history and record, and have two colleagues do the same, before we could judge whether the total level of promise merited further review. Since we admitted 13 this year, we needed all three rounds of review just to get to the top 10% that you assume could be skimmed to with little effort. When we say that admissions are "competitive", we mean that they are competitive - i.e., not just that there are a large number of applicants, but that decisions are very difficult and there are many excellent candidates, most of whom won't get in."
I'll let you decide who's better informed: Loric or a T20 DGS.