I have to agree, if this site was allowed to cover those OS's, then all we would have is another general Windows forum, which there's plenty of already. This should primarily remain a Windows 7 forum.
I too, have some older Windows OS's (from 2K through Vista), as well as Linux Mint 9, but I'm a member of the forums of the OS's that I use. That way, I can get the help that I need, plus as on here, I can in return help others.
Don't get me wrong, there's nothing at all wrong with using other OS's and having choice over what you run. I strongly believe in the freedom to run whatever OS (or OS's) that we want. There's several Linux users here, and I'm one of them. But it would be a distraction to look for help with Linux here, as well as the older OS's that I run.
But to have an all OS, all brands of computing, would take a massive effort, and would be difficult to run properly. This is not the largest forum on the net by a longshot, but it's the best that I've ever been on. From Ian on down, the people here have been good to me, and everyone is treated the same. There may be dispute and debate, but that's just everyone sharing their opinion, and very seldom have I seen Ian or the mods have to step in to break up a mess.
With this and the above posts in mind, it's best that we remain as we are, a group dedicated to Windows 7, as it's the present, and there's many challenges that remains ahead of us here. Computing is advancing everyday, and we have to do our best to keep up with what's new. We cannot move forward by embracing the past, and these are all the more reason that we must remain on our mission here, learning all we can about Windows 7, and helping our fellow members in need.