You should know what OS (version of Windows) you are running, you get a full-screen logo of it every time you turn on your computer. If you still need to check, look at the General in the System control panel.
Other specs that would be useful are your video card type, CPU speed, and amount of RAM. Your CPU speed and RAM are displayed on the Current Settings tab in FF8config, and also in dxdiag (go to Start -> Run and type "dxdiag".) The Display tab in dxdiag will tell you the name of your video card and how much memory it has.