I've been a user of Calibre since... well I don't even remember when. I think 0.9.something. It's awesome and I love it. I donated at least once, maybe twice (I don't remember exactly). I use it every day.
I noticed that the latest installers from the 5.x series don't want to install on my computer anymore. Today I had some time to dig through github, and noticed that a check was added to prevent it from running on Win7. Oh well.
I understand the reasons, and I'm not upset about it. I feel that I got a good run for it, and a good value for my donation. Version 4.23 which I have installed currently works flawlessly on 7, so I guess I'll just untick the "check for updates" and keep using that.
Again, thanks for all the fish.