Hi,
GMAT : 640 44q/34V
Total exp: 4+ (TCS,IBM and currently in Tech Mahindra CoE center of excellence team)

Which schools can i target? I'm looking at 1 year programs. Post MBA I would like to work in Pre-sales/Marketing. Can I get financial aid or scholarship with this GMAT score.

My target school is Great Lakes chennai. I would like to keep other options as well. What are my chances in NUS,NTU ? Should I try for Bschools in Canada n NZ as well.

Since your work background is very common among Indian applications to Singaporean business schools, you will need to substantially improve your GMAT for NUS or NTU. Take a look at the tier 4 schools at http://www.find-mba.com/board/27082

From what I understand about Great Lakes Chennai, the average GMAT score is much higher than 640, so I doubt you'd be competitive.

And like Duncan said, the same would be true at the schools in Singapore. If you can bump your GMAT score to 680 or so, you would probably have a better chance.

As for schools in Canada and New Zealand: You might be able to edge in at HEC Montreal, but I'd still consider that a reach school considering your profile. Maybe you'd have more luck at Auckland or Otago in New Zealand?