MS in computer science

I am currently working as a web developer in a startup (pretty exciting btw). Firstly I have done B. E Mechanical and have no interest left in this field for what so ever reasons. Secondly my marksheet is horrible and as one guy said I rarely stand chance for getting admission so I had given up but now I am seeing people with a slight better marksheet than me getting admission after 1 or 2 years of application. My aggregate is barely 50% but I am a potential programmer and enthusiastic about computer related stuff.