Hi Carrie,
If you have Acrobat 9 or X Standard, or Acrobat Pro 7 or higher you can add Reader Enabling Rights to the PDF that will allow user with the free Adobe Reader to both fill and save the form. The location and name of the menu command to do this has changed in pretty much every version of Acrobat since the fature was introduced. You will find it under the Advanced menu in Acerobat 7,8 and 9 with wording similar to "Extend in Adobe Reader" or "Enable Usage Rights in Adobe Reader"...... In Acrobat X it is under the Save-As menu with similar wording. After you have selected that menu item just follow the dialog prompts.
After you apply the Rights pretty much any editing to the form will break them and they will need to be reapplied. So only add the Rights after you have the final form design.
Hope this helps,
Dimitri
WindJack Solutions
www.pdfscripting.com
www.windjack.com