That's a pretty broad question. I did an unscientific look at the properties that sold during the month of August 2009 and found an average of 84 days. However, that doesn't tell you much of importance. Cheshire County is a large area and home sales in Keene are not entirely comparable to home sales in Winchester or Fitzwilliam, for instance. Also, the type of house you are interested in makes a big difference- a large luxury home may linger while a more compact family home sells quickly, or a fixer upper may have to wait for the right handyman while something in move-in condition doesn't.
If you are considering selling a home ask your agent for a written CMA, including comparable sold and on the market properties. Seeing a few homes in your area that have sold recently and that compare to yours will give you best idea how quickly and at what price you can expect to sell.
If you are considering buying it isn't quite as easy, but you can ask your buyer's agent for similar help- what price and days on market info is for homes in the specific area, style, and size you want. Look closely at the market history- it will tell you a lot.