I would vote MS Office 2007 built in feature "save as pdf" as one of the best option.  Cutepdf is great because it acts as a printer and prints anything (docs/ spreadsheets/ power points/ webpages) as pdf.

In case you want to the other way i.e. convert pdf to word Hellopdf  (freeware) might help you a lot. But you need to beware  when the file size is big and when the pdf has multiple pages with too many details...It will exhaust all your system resources...