I moved back to Windows on my home computer a few months back. There are a few amazing free tools I've found since then that have been making my life better and I thought they deserved a shout-out. They are:
A fantastic PDF reader. Does everything I want and nothing I don't.
A sane way to edit environment variables. The simple joy of just being able to resize the window is... incredible.
The best tool for dealing with compressed files on windows, bar none.
A really handy way to see details about your GPU(s).
An amazingly good image viewer, which can also do bulk file format conversions.
If you haven't already got these... go get them!