Let's say your form was this:
Type of Trombone: Dropdown (small, medium, large)
Color of Trombone: Dropdown (silver, gold, pink, other)
How many years have you played: Textbox (number 0-99).
So when a form was filled out, this data was posted to a thread.
Digitaldoctor has a Large Pink Trombone and has played (with) it for 9 years.
Do you want all that information in a database ?
So you can produce statistics ?
What if your site had Trombones for sale, would you want to do a mailing to all the Trombone users ?
If another question was:
Do you give Trombone lessons ? Choose: (Y/N).
Would you want Trombone learners to be able to contact your Trombone Teachers ?
The idea here is: Do you want the form data stored such that you can use it ? or just post the text to a thread ?