The box that your PC was packaged in must have the serial number of the machine. If the machine in question is a desktop PC, check the back, top, or sides for stickers. The sticker with the serial number may also be inside the PC’s casing, meaning you might need to open it up. See our List of Free Key Finder Programs for a number of completely free tools that will do all the hard work for you, surfacing the Adobe CS serial number you need so you can reinstall your copy of Adobe CS6 Master Collection, or Adobe Photoshop CS5, etc.
What is my Computer ID? Your Computer ID can be found by RIGHT-Clicking on your 'My Computer' icon on your desktop, then clicking on 'Properties'. Clicking on the 'Network' Tab, you should see something like this. Your computer name can be changed, typically by an 'administrator'.