What I strongly suggest you do is to continue working for a few years (at least for another year) before even thinking about b-school. You just graduated this summer and you're already wanting to go back to school?
Work (or continue finding a job if you don't have one). Get some real world experience under your belt. It'll be better for you once you're back in b-school - in terms of perspective (what you get out it), admissions (getting in), and recruiting (your resume will be stronger). And in the meantime, find a way to boost that GMAT score. If you're really looking to do investment management, you should target the best schools you can get into, and ideally at least in the top 50. For those sorts of schools, you will need at least mid-600s for the bottom half of the top50, and high 600s to 700+ for those in the top 30 and above.