Vishy, I personally know two people with Indian MBAs who went to pursue full-time degrees from top American B-Schools. One graduated from IIM-B and went on to become a Wharton alum and the other had a regular Indian MBA and went on to pursue his MBA from Chicago. So, there is definitely hope for you, even at full time programs. But do take this with a grain of salt as both people mentioned above had
stellar stats - GMAT, work-ex, reccs. I mean
stellar.
To sum up, do your research, re-take the GMAT (if you are looking at top schools) and work your a$$ off on those essays.
P.S: To those of you who don't know - the IIMs don't award MBAs. They give you a P.G.D.M (Post Graduate Diploma is Management) which they say is
equivalent to an MBA. So someone who went to an IIM and then went to a US School really has only one MBA in terms of the name of the degree. That's probably part of the reason US schools are open to such applicants...