GMAT Strategy

I want to apply for a masters in finance and wanted to know from fellow members what their perception of a GMAT score would be for an application for an MBA vis a vis a Masters. Are the scores evaluated differently (weight-age to an application)? My perception is that a masters may require a high GMAT score and may emphasize less on work experience and extra curricular activities. Please do throw some light on the same. I am getting an average of 550 on prep tests and am scouting through the forums to strengthen my weaknesses but would like to know my application position in context to the GMAT prior to applying.

I'm not sure how this works for other countries but for many schools in the United States the GMAT avg(as published by the school) is higher for MS programs than the MBA program. For example, in my target School the MS avg is 610 but the MBA avg is 580. Avg Work ex for MBA is around 4.5 years and 3.5 years for MS.
Hope that helps.