does your school have a placement service you can still access? You might just need to do a better job explaining why they should hire you.
If people are telling you that you are too qualified for the job you want, then they are probably afraid that you are going to leave right after they spend the time and money to train you. If that is the case, you need to reassure them that they won't waste their investment. It can be a balancing act between letting them know that you want opportunities for advancement with them, but that you aren't using their job as a temporary stepping stone.
If you are being told that you don't have enough experience, then you may just need to explain to them why you have the skills they need. You might try a skills based resume rather than one that focuses on job history. Pick out the skills you learned from jobs you have held (e.g., analytic skills, communication skills, teamwork, etc.) and document projects you've worked on and job activities to back up that you've been successful employing those skills.
Also, target your resume to the job you are seeking, even if you have to write a new one for each job. Recruiters see LOTS of resumes and they have to narrow them down before they can process them. They are human, so they are going to base a lot of it on first impressions. If your objective is too vague or wishy washy or doesn't seem to fit, that's a reason to toss your resume (of course, if it looks unprofessional or you have words spelled wrong then it will go in the trash, too). If your resume looks like exactly what they want, you are more likely to get an interview. It will also help with the "over qualified" problem.
There's more job advice here:
http://www.quintcareers.com/career_resources.htmlhttp://www.collegegrad.com/Good luck!