Hi Deepa,
A GMAT score of 640 is really low. It would be difficult-but not entirely impossible- to get into top business schools with this score.
We could better comment on your chances, and the schools you could get if you provide us more information on your work experience and extracurricular activities. If I am assuming correctly, you must have rich work experience at Intel with stories of leadership, result orientation, team skills, and ability to work hard. Carnegie and Intel are good brands on your resume.
Though your work experience is on a higher side, you need not worry about it as we have seen people with even 10+ years of experience. What matters is how you showcase your experience in your essays. If you can show a strong experience over the last 9 years with increasing responsibility and results, I think it should be fine.
If I were you, I would retake GMAT, and get a score above 700. It would increase your chances at the top business schools. Full-time MBA is anytime better than a part-time MBA. Full-time is expensive and risky but the rewards are higher. I don’t think it will be very difficult for you to get into any part-time program. If I were you, I would aim for a full-time program.
Good luck!
https://www.InterviewBay.com- Application Reviews and Mock Interviews by Alumni of Your Target School