Janardhanan,
You need to be able to show that you have lead projects for at least 4,500 hours (or 7,500 hours depending on your background). Therefore, first list all the project where you were the project manager. If that brings you to the required number you can stop. If you still need to show more hours, then begin listing those on which you were a project participant.
Please see
www.pmi.org/pdf/pdc_pmphandbook.pdf
to learn whether you need 4,500 or 7,500 hours.