Questionary Development

I have a form that contains 100 questions. To make it easier on the user, I will divide it into 5 sections (20 questions per section), then all the information will be written to a db. What is the best way to carry along through the pages the information that has already been submitted? Cookies? Writing to a DB after each section? Session Variables? I read that writing to a database as i go along could be too much of a hazzle for the db, specially if I have multiple people filling out the form at the same time. TIA -- ....helmut helmutgranda.com