2015Applicant

Hi everyone, I am looking to apply to top universities for admissions into MPP/MPA in the 2015 school year. I am starting preparation early as I think the sooner the better. Some of the schools I am considering are HKS, SIPA and WWS. Alternatively, I might also apply to LSE and Oxford. My question is I have quite a horrible GPA 2.24 in B.Sc in Business Administration from CMU. Since graduation in 2009, I have worked in non profit and government sectors. I am currently employed in project coordination and management role at a national level government organization since 2 years and a half. Over all, I have experience of about 3.2 years with some gaps in employment (due to recession about the time I graduated and ofcourse my gpa). I am not asking whether I can get into these schools because that is something nobody can predict. I would like to know how a great performance at a graduate certificate will be considered in admissions. I am looking to pursue online Graduate Certificate in Policy Analysis from Pennstate. Hoping that I do really well in this program, would it offset a bad gpa ? Any advice or opinion is welcome. Thanks in advance !