Hi GmatEnlighten,
It's important to define what YOU want out of an MBA. If you'll take ANY MBA that you can get, then there are Schools that might accept you with a 500, but you should note that none of them will be in the Top25.
Here are some things to consider:
1) Do you want to work in a particular field or for a particular company?
2) What do you want to be doing in 5 years? 10 years?
3) Are you willing to relocate? Are you willing to go through a program that is primarily online?
4) How big a factor will the cost of the program be in your decision?
Etc.
There are plenty of other 'variables' to consider, of course, but you have to define what you're after, so that you can proper assess the possibilities. Earning an MBA requires a large investment of your time, energy and resources, so it's important to make sure that the MBA is worth it.
GMAT assassins aren't born, they're made,
Rich