Abbyy FineReader Express 9 ($99, 14-day free trial) is a nice little Optical Character Recognition program for converting scanned images into editable word processing documents. Not as nice as the professional version, which has an updated and more effective recognition engine, but still darned good OCR--especially for the price.
FR 9 Express is extremely easy to use. A new tasks dialog pops up when you first run the program presenting you with the most common tasks: scanning to PDF, opening images for OCR, etc. There's also a pane the shows you the things you're missing by not owning the professional version, such as proofing and editing, better OCR, conversion to editable PDF, etc. Thankfully, you can hide that pane and get on with your business.
FineReader 9 Express supports output to normal PDF, rich text format, Excel, and HTML. Conspicuously missing is Microsoft Word's .doc and .docx formats. In my hands-on with about 20 different scanned images of documents, FR 9 Express did a very nice job recognizing normal text--virtually flawless. It was also effective grabbing text from challenging graphics--at least with 300 dpi documents. It failed completely with a couple of difficult 150 dpi scans that the professional version and its competitors were able to render into text, instead leaving them as images.
If you don't have anything particularly challenging to scan, and aren't worried about creating editable PDFs, then FR 9 Express will do the job. If you need to reconstruct more complex documents accurately, you'll need to spend more money for one of the pro-level solutions: Adobe Acrobat X Pro, Abbyy FineReader 10 Professional, or Omnipage 17 Professional.
Note: If you plan to buy a scanner, it may come bundled with OCR software. Many include FineReader Express or other lightweight versions.