I received a form in PDF format that has fields to be filled in.
I coulld not type in the fields in my computer that has Win 7 or in my Mac Book Air that has Snow Leopard.
The pdf form protection -> Security Properties-> has "filling of Form Filelds" as -> Allowed.
Are you sure those are real fields, and not just graphic elements that looks like fields?
At any rate, if they are fields but they are locked, for example, then there's nothing you can do. You need Acrobat to unlock them.