I totally agree with awesomeusername - your scores for the kaplan are very okay (the kaplan by the way is not reflective of yoru final score in GMAT at all, they say its 50 -60 points below what you will finally get as the exams are too hard). Your your gmat prep scores however are fairly low. The gmat prep at the end of the day is a reflection of what you will score in the exam.
the princeton tests that I took, were very very helpful as well. As awesomeusername mentions, I started out in the worst way possible (knew almost nothing in maths and verbal - took me 6 months to get a 700+ score). I believe if I gave GMAT again now I wouldn't score more than a 400 again ....
Its about reading the concepts from the books, keeping all the formulae, and the tips in mind, getting your timing nailed down - its not a true measure of your caliber at all, for me I think it was more about how organized I was in my study approach, My ability to work from basics/concepts up, and finally a measure of my perseverance, and will to succeed. Its not fair I know - but well, if thats what it takes to get to a B school, thats a pill I was willing to swallow!
I hope you do read my debrief and find it helpful - I tried to jot down everything I could think of which was important there. (Its in the main forum right above beatthegmat/erics blog.
Take care,
-ngufo
People Never Fail ... They just Give Up