Windows PDF viewer that auto-refreshes PDF when compiling with pdflatex

SumatraPDF is free, for Windows, and plays nicely with LaTeX. It will automatically refresh when the pdf is updated.

There's an Evince version for Windows.

I know the question is old, but I think an important option is missing.

As a lot of people use MiKTeX on Windows they already have TeXworks installed. The PDF viewer included with TeXWorks does indeed refresh.

start texworks main.pdf

or right click any PDF file and select to open with TeXworks.

I'm not saying that the PDF viewer itself is the best, but it's very convenient (if you have MiKTeX) as you don't have to install yet another PDF viewer.