If you have the full version of Acrobat -- not the reader -- you can simply
save as word (or as RTF, which Word can read, in earlier versions of
Acrobat). The quality of what you get depends on the application that
created the original. If it was created from a Word document in the first
place, you usually get pretty much what you expect. If the original was
something like Corel, the output to Word will look like nothing on earth.
Text will still be readable, though.
There are some freebie Acrobat clones around that do it also, with the added
advantage(?) that they ignore the PDF security settings.