Hi,
I have been reading the forum for the past one month. And that's the same amount of time I prepared for GMAT, which I took today. I used OG and Kaplan for preparation. These are the scores that I obtained on some of the tests :
GMATPrep1 (Before I started the preparation) = 620
Kaplan CAT 1 = 650
Kaplan CAT 2 = 690
Kaplan CAT 3 = 680
MGMAT (Free Test) = 710
Knewton (Free Test) = 710
GMATPrep1 = 730
GMATPrep2 = 700
GMATPrep1 = 720
GMATPrep2 (A Day before the exam) = 740
GMAT = 660 
I am highly disappointed

(and angry) by my performance and as I was targeting the first round of applications, I am extremely tensed. I made a big mistake towards the end of Quant section.I could not click "confirm" for the last question and the time was up. So I guess that resulted in a serious penalty.
I would like to know if I stand a chance of getting admitted to top 20 universities in the US(such as Ann Arbor, Carnegie Mellon amongst others). I have 3 years of work experience, with one year in the IT industry(worked for the largest auto insurer provider of US) and the rest in Market Research(with some additional responsibilities in IT as well). If not, would a retest and application in the second deadline be a better option?