USA Today reports that Microsoft has announced that it will make its new Windows Vista operating system available online for download, marking an important new step for the company. Previously, Microsoft has only sold operating system software through disks or pre-loaded on PCs. While a low number of users are likely to download Vista, this step suggests that Microsoft is beginning to tweak its distribution methods. The downloadable version of the program will also include Office 2007. Initially, the downloadable version of Vista will only be available in North America…