My salaries was paid by my employer in the form of grant
Every yr my employer send 1042-S for tax filing
I know that there is $400 tax credit
I am filing 1040A form for this year (2009)
Can I claim this credit?

If you are getting under Form 1042-S, that implies that you are a foreign student and PROBABLY a non-resident alien.

If so, you are NOT eligible for the $400 Making Work Pay Credit.