If it came preinstalled on your computer it depends on whether you replaced the motherboard with the manufacturer's replacement part or you bought an upgrade board of your own choosing. If the former you can reactivate with Microsoft by phone.
If the latter you will need to purchase a full license copy of Windows. If you purchased Windows 7 Ultimate seperately (retail) you can simply reactivate. Please follow the instructions in announcement 1 above so we can tell what you have.
In order to receive the best support, we request all users initially download and run the Genuine Diagnostics tool (MGADiag.exe) at this link
http://go.microsoft.com/fwlink/?linkid=52012. Click "Continue", click the "Copy" button then “Paste” the report into a reply message in
your own thread.
Colin Barnhorst Windows 7 Ultimate x64 on DIY with 6GB ram.