I am a big fan of Ward Cunningham's quote "What's the simplest thing that could possibly work?". It is not as easy to follow as it sounds. Just today I found a nice example.

I regularly update the software which comes with every ThinkPad. The update tool looks pretty cool at first sight. It is simple, reliable and just gets the job done. Well, not exactly. Today, I wanted to clean my harddrive and discovered this folder called drivers where the update tools stores the updates. The folder is now 1gb big and stores only drivers which are already installed. So I began to suspect that the download update tool compares my local folder with currently available updates on their servers. A quick test confirmed my assumption. What does it mean? It means that I cannot get rid of the garbage because otherwise the automatic updates will not work anymore.

What about using a file for storing the information about already downloaded software or even better ask Windows which driver and software versions are currently installed?