I've done it now...

[MikalE]

I upgraded (downgraded?) my highly modified T520 to Windows 10 Pro.

I locked it down as best I could with no Cortana, Bing, or anything else provided by MS.

The speed increase with the new quad-core i7 processor I installed is terrific. Things move along much faster in 10 than they did in 7. I'm not unfamiliar with 10 as I have it installed on an i7 T510 that came that way.

I was surprised though, when after purchasing Windows 10 Home at $120 that I ended up with Windows 10 Pro installed. ??? I didn't pay for that, but I was upgrading from Windows 7 Pro, so I guess the download server knew that and I got a free upgrade. ??? Is that normal?

I know when they were handing out free versions like candy you got the Windows version you had to begin with, but when they started charging I thought you got what you paid for regardless of what your old OS was.

[MikalE]

In addition, Bluetooth 4.0 works flawlessly now. The JBL Flip4 speaker I had been having trouble with connected right up to the T520 and I was playing audio through it immediately.

Also, the wireless connection is immediate upon scanning my fingerprint and the system comes up. Boot time is about eight seconds now from sleep instead of 30-40 that it was on Win 7. Cold boot time is about 25 seconds instead of the minute or more on Win 7.

Audio still sucks as I knew it would. Hence the Flip4 speaker.