Amazon Sales Ranking Sampler

I recently wrote a book that is being sold on Amazon and Barnes and Noble. [login to view URL] has in the description a line that says? **[login to view URL] Sales Rank:**? #163,781 in Books, which changes frequently (must be a time-decaying moving average of some sort). I would like to be able to track how this rank changes over time. I'd like a small background application that samples the site periodically (say, every 15 minutes or at an increment I can set) and saves the data to a file I can read into Excel or otherwise chart. If the charting is built-in, it's a plus. I don't much care about the language the app is scripted in, but I am running a Windows XP machine.