Drew would like to know where he can download older versions of Windows. He has an old laptop that he upgraded to Windows 10. He's installed VirtualBox onto it so he can run an older version of Windows as well, but he can't find his old Windows CDs anywhere. Leo says that Microsoft offers older versions to developers if he gets a subscription, but it's not cheap.
He may find it at oldversion.com, but they're not legal. eBay is a good option, and it's safer too. Amazon may be able to sell them as well. The problem is that there's no activation anymore for versions of Windows older than ME.
Drew also needed to find DOS, and for that he could use FreeDOS. It's open source. One thing he could also do is make an image of his old OS after installing it and then just reinstall that image.
The chatroom also found a technote that Microsoft has made the source code for old DOS versions available. Other places include allbootdisks.com and this page at winworldpc.com.