Define "decent university." Something to note...some idiot got into Harvard with a 490 gmat last year. You scored higher than that person/moron. But anyway, yes, you should retake the gmat. Unless the rest of your application is super strong, a 550 will hurt you. Certainly, high scores do not really help students matriculate to top schools, but low scores certainly cast doubt upon an applicant's MBA aptitude. Raise your score to a level within the range of your target school. Then focus on the rest of your application.