Rather than mod you down : 64bit servers is where it was at. All those AMD64s in the data centre with >4Gbs RAM
XP64 was crippled by bad drivers.
I wonder if Alpha would have succeeded if, in addition to NT, Microsoft ported Office, the whole BackOffice family and Visual Studio. It's not that hard to blame them for the fact we still use hypertrophied 8080s.
No. For most people, Microsoft brought 64-bits to the PC world. Had Microsoft decided not to support AMD64 in Windows and opted for some other 64-bit x86 architecture, AMD64 would be a curiosity.
It's a bit sad because I remember reading AMD's announcement on a 64-bit RISC workstation that was already a bit too old compared to its newer cousins.