All you need is to make the recovery cd's. Thats basically what best buy does and charge you for something you could have done yourself. The recovery cd's are used when disaster strikes and your hard drive fails so you can reinstall windows all preinstalled apps back on to a new hard drive.
Now if you are talking about backing up your data, thats a different thing. You can create an image of your OS and installed programs and data and store it on an external drive and then when the hard drive fails or you need to reinstall windows, you can reimage the drive and be back up and running in less than 30 minutes. You can use Acronis True Image software to do this.