Here is a nice tip to learn the install date of your Windows operating system. Why one would want the install date is simple. You might just want to restore a backup you made after a particular date. Or you might want to review when you first bought your computer and installed Windows. Regardless of it's uses. It's a great command to learn with quite useful information.
go to DOS prompt and type "systeminfo" one word with no spaces and just look for a line item that saids Original Install Date.