Create another windows user and run samp as this new user.
The GPCI hash is created from the san andreas folder location in the documents and settings.
The entire location is hashed, including the windows username. So by running samp as a different windows user your hash will be completely different.
Ignore all the HWID and clueless talk. These people know nothing. there is no hardware id being recorded. Unless 0.3z changed this, haven't bothered checking