Once you get a Microsoft rep on the phone, explain to them all that you have been through with this machine. They're usually pretty good about helping you get things right. Your issue isn't with legality, it's just been worked on a bit much and gone through a few hardware changes.
Click Start, point to All Programs, point to Accessories, point to System Tools, and then click Activate Windows.
Click Yes, I want to telephone a customer service representative to active Windows now.
Click "Read the Windows Product Activation Privacy Statement", click Back, and then click Next.
Follow the steps in the Activate Windows by phone dialog box, and then click "Next". A phone number will appear based on your location...call it.
When activation is completed and you receive the following message: "You have successfully activated your copy of Windows" click "OK".