I am a bit freaked out about how painless this was. The experience was surreal to someone of my vintage.
My primary machine is a 10 month old MacBook Air with 8GB of RAM, 1.6GHz i5 and a 256GB internal SSD running Yosemite. A Thunderbolt 2 Hub connects an USB 3 external 1TB SSD and an old Firewire 800 3TB external drive and separate 3TB backup cradle. All pretty generic stuff.
For work reasons I bought Office 365 Mac. I thought I might be able to avoid Windows entirely, but a new contract meant I couldn’t escape.
So I installed my Fusion VM 7.x and an old XP image with Office 2007. The image is stored on my external SSD. That went disturbingly well, so I downloaded the Windows 10 ISO (64 bit) and asked Fusion to create a new image from the ISO. That also went disturbingly well. The only glitch was it hung during VMWare Tools installation. I had to restart the VM and I reinstalled the tools.
Then, hey, what the hell, I installed Office 365 too. The usual 365 license covers several machines, both Windows and Mac. Yeah, same thing. No problem.
The image on the external SSD took 12.6GB with just Windows 10 Pro, 14.45 after Office 365 installed. Heck, I’ll probably move it back to my primary SSD.
The performance of my very generic low end MacBook Air is excellent. Modern SSDs are a miracle.