For pursuing MS in comp science ,you will have to get a gre score.A good gre score anything above 1400,moderatlley ok 1200-1400 if you have got good recommendations from your professors.
Next thing if you want to do MS in computer science and you are from electrical ,you may have to take some prerequiste courses.A guy i knew from meachanical branch but had 2 years experience in some IT company had to take 5 pre requisites.So 5* tution fees per subject + an extra year to get the degree.This pre requisite changes from college to college ,but i think any good college will definetly ask to take pre requisites courses.
The major factor is money to do MS in USA ,that is if you cannot get a scholarship,even if you get a scholarship monthly expenses in USA is very high when compared to INDIA, .If you are ok with that ,then go for it .But if you are relying on some loan or hoping to get a job when you go there ,then it would be risky.
Then there is a 4C rule ,which means if you get 4 C's you will be kicked out of college,its there in some colleges thats for sure.This is just to inform you ,things like this i hardly doubt any consultancy or even the universitiies to which you are applying will tell.
Dont believe any consultancy services they are thugs ,survey a lot when you choose a university .Check this site msinus.com ,it might be helpful.There are communites in orkut ,they are very helpful as you can get info from the students themselves.