To find the date of installation, simply find the folder named "config" within the windows folder. If you right-click it and view the properties, it should display the date it was created; the date windows was installed. To answer your second question, XP Pro offers more support for users who wish to create home networks, and tends to me a more reliable operation system. It depends on what you plan do with with your computer that determines if it's worth the extra money. I Hope I was able to help!