There a number of programs that will do this, but there are some workarounds if you have a scanner and an OCR program. Also, if you have the full version of Acrobat 6 or Omnipage Pro 14, both have the ability to convert into a Word doc in some way and there are some specific PDF converter programs available. However, if you want to do this quickly and it's a one time thing you can accomplish it by printing out the document from the pdf. Scan and run the OCR program. Save to word. Most OCR programs have a wizard of some kind to walk you through this. It probably will not be a perfect copy of the pdf, but you will be able to work with it.
No scanner, then get a PDF converter program. It's definitely cheaper than a scanner. Worst case. I've gone to Kinko's and asked them to scan and convert when my system was down. But, IMHO, buying the program would be cheaper. Hope this helps.