Hi sarahf93,
To answer your immediate question: YES - the Quant and Verbal sections are the only two sections to contribute to your overall Score (out of 800). That does NOT mean that you should avoid preparing for the IR and Essay sections though. For example, many Schools expect Applicants to be able to score at a minimal level on the Essay (that typically means a 4.0 or higher out of 6.0) - and Schools can actually ask GMAC for access to read your Essay response. As such, you wouldn't want to do anything lazy or careless with that part of the GMAT.
Before I can offer you any additional advice, it would help if you could provide a bit more information on how you've been studying and your goals:
Studies:
1) How long have you studied?
2) What study materials have you used so far?
3) Have you taken any practice CATs/mocks yet? How have you scored on EACH of your CATs (including the Quant and Verbal Scaled Scores for EACH)?
Goals:
4) What is your goal score?
5) When are you planning to take the GMAT?
6) When are you planning to apply to Business School?
7) What Schools are you planning to apply to?
GMAT assassins aren't born, they're made,
Rich