I am currently a second-year MBA student. I decided to retake the GMAT to get a higher score for my PhD program application. Here is a story of my battle with the GMAT:

Round 1: Fall 2008
Took 2 months to prepare. Used Manhattan GMAT, OG 11 and OG V and Q. Highest score on GMAT Prep - 620.
Result: 650 (Q42; V38) Got accepted to the MBA program.

Round 2: Summer-Fall 2010
Took 4 months to prepare.
Used:

Manhattan GMAT (2007 ed)
Kaplan GMAT 800
OG 11, OG V and Q
OG 12 (some parts)

Practice tests (most tests w/ essays and under official conditions):

Princeton CAT - 610 (Q42; V33) - 7 weeks before the test
MGMAT CAT 1 - 680 (Q44; V38) - 4 weeks
MGMAT CAT 2 - 620 (Q40; V35) - 3 weeks
MGMAT CAT 3 - 680 (Q44; V38) - 2 weeks
GMAT Prep 1 - 740 (Q 49; V42) - 1 week
MGMAT CAT 4 - Q 43 (didn't do V) - 4 days

September Result: 670 (Q39; V42) Had a very stressful week at work before the test - didn't feel well on the test day.


Round 3: October 2010
Took one month to prepare

Practice tests:

MGMAT CAT 5 - 680 (Q44; V38) - 2 weeks before the test
GMAT Prep 1 repeat - Q48 (didn't do V) - 10 days
GMAT Prep 2 - 730 (Q49; V41) - 1 week
GMAT Prep 2 repeat - Q46 (didn't do V) - 4 days

October Result: 650 (Q42; V38) The same result as 2 years ago.

Should I retake it in November? What resources should I use to prepare? Is OG 10 any good? I would appreciate any ideas. Thanks