The Microsoft Office Suite has something called the "Microsoft Office Document Image Writer" which provides a virtual printer which creates TIFF files as output. If you have it installed, you can then "print" any Word document or PDF with it to convert them. You may be able to do the same thing with the virtual Fax printer built-in to Windows which has an option to create TIFFs instead of faxing them when you print to it.
Adobe Photoshop (and Photoshop Elements, I believe) have the ability to read PDF files and then save them in a number of different image file formats including TIFF.
As far as free software goes, although originally and primarily Postscript-oriented, you can also use the high-quality Ghostscript program to convert PDF files to a number of different image file formats (see Details of Ghostscript Output Devices). There are also some nice output viewing utilities for it.