Basically, a long time ago I made a OS Thread. I admit the OP sucked. Now I'm going to try and make a better OP.
Windows:Windows Vista:
Successor to Windows Xp, it was released on January 30, 2007. It included many new features to the Windows OS like a new GUI and multimedia tools. Windows Vista primary focus was improved security. Some criticism of Windows Vista is it's high system requirements.
Summary: Don't get Windows Vista if you have a stuffe computer.
Windows 7:
Released on October 22, 2009, it introduced a lot of new features like Vista did. It's new features included a new taskbar, Windows Calendar, Windows Mail, and more.
Summary: Sometimes Windows 7 can cost some money, but it's a pretty good OS all in all
Apple/Mac:OS X:
OS X is commonly named after big cats like mountain lion. Although OS X commonly has updates the first version was released in 1999. It originally ran on PowerPC-Macs, but in 2006 Intel Macs could run OS X.
OS X V. 10.7 was the first version to have 32 bit and 64 bit Intel processors.
Linux:Linux is a very diverse system, so there are many types for many different people. There are Linux OS's for server hosters and other stuff. Since it would be hard to show you every single OS that Linux has created, I will give you the link so you can look through it and decide for yourself.
Link:
http://en.wikipedia.org/wiki/List_of_Linux_distributions