Microsoft's new Digital Locker system allows users of Windows computers to download computer software from a variety of vendors. A number of software vendors already provide this functionality -- Microsoft's system brings those vendors under "one roof", manages the financial transactions, and then stores the license information for later use if your installation croaks.
Using the familiar shopping-card functionality, users can browse the software listings, and pick out what software they would like to download, and then purchase the items. Once the finances are arranged, a separate program called the Digital Locker Assistant will manage the downloads, and allow you to burn the images to CD / DVD media for offline storage.
I like this idea, and can see it being useful for the consumer market -- the Corporate people with their bulk licensing agreements at discount will probably not use this system much, but for the consumer market, I can see great value in this functionality.
I have made online purchases in the past from Adobe and Macromedia for my Macintosh, and found that I like the idea of getting the software when I need it without having to go and get it at some store somewhere. I can start the download, walk away, install, and backup all while doing other things. But I do have to keep a separate database for my serial numbers, and do keep them printed out and in a file cabinet for easy retrieval.
In order to use the Windows Digital Locker, you will need a Passport account, and you will need a credit card to work with. I am not sure if the site requires IE as a browser, and I did not see anything on the FAQ or directions about working with other online financial packages such as PayPal.