My Amazon-purchased Windows 7 upgrade which I clean installed as x64 now shows the "Windows 7, Build 7600." It appeared after reseating a clumsily installed memory module, updating nVidia drivers and adding Divx player and codecs. Not sure which (if any) of these might be involved. I am activated w/ Microsoft. I see the watermark removal utilities but I'm wondering why I'm marked in the first place. Thanks.