proTeXt aims to be an easy-to-install TeX distribution for Windows, based on MiKTeX. After downloading, a wizard (available in several languages) guides the installation.
You can download the self-extracting protext.exe file from CTAN; it is well over 2GB. That link will automatically choose a nearby CTAN mirror. If problems with the download, please manually choose a mirror from the list.
If such a large download is problematic for you, proTeXt is also included in the TeX Collection, which you can get by becoming a TeX user group member. On the other hand, if you have plenty of bandwidth and want to burn your own DVD, you can download proTeXt as a giant ISO image.
Once you have the distribution, you can start the installation by running Setup.exe (if it does not open automatically). At present, proTeXt includes only 32-bit binaries, but runs fine on 64-bit systems.
New users can find starting points for actually using TeX in this introduction to the TeX system.
proTeXt adds the TeXStudio front end to MiKTeX. If you want to see the exact contents of the distribution, the .exe file is also a zip file; you can inspect it via unzip (on any platform).
To use ConTeXt within proTeXt or MiKTeX, you also need to install a Perl for Windows such as ActivePerl, and Ruby. (Later versions than the ones linked to here will most likely work too.) The contextgarden wiki has more information on MiKTeX and ConTeXt.
All past releases of proTeXt have been publicly archived.
proTeXt's creator and principal maintainer is Thomas Feuerstack, while MiKTeX was created and continues to be maintained by Christian Schenk. Many thanks to both.