What exactly is included in the proTeXt's 1.1GB package and why would you rather download that compared to just downloading the humble 170MB MiKTeX basic install?
Also, why is proTeXt's file size so enormous?
Update: The current proTeXt actually contains TeXstudio as an editor, and not TeXnicCenter anymore, but that information hasn't even reached all of their own web sites yet.
TeXnicCenter is a LaTeX editor that works quite well with MiKTeX, Ghostscript is software for processing PostScript (*.ps) files.
What makes the difference between MiKTeX's 164 MB and proTeXt's 1195 MB is the fact that MiKTeX is a Basic Installer that loads further packages on-the-fly, when necessary. The MiKTeX included in proTeXt has that ability, too, of course; however, it comes with many (all?) packages included, so it's a "full" install.
If you're completely new to LaTeX and you have a decent Internet connection, I recommend going for proTeXt because it gives you all you need for a start and offers a nice installation-flow manual.
If you kinda know where you're going and you have Internet access whenever you need it, the Basic MiKTeX Install will suffice. You can complement it with an editor of your choice, some are listed in the qustion LaTeX Editors/IDEs, you can see which are quite popular among tex.sx users in our TeX Community Polls.
One last thing about MiKTeX vs. TeX Live: I started out using MiKTeX about a year ago and I have found it quite comfortable; but as time goes on, I'm thinking more and more I might switch to TeX Live soon. Some differences are discussed at What are the advantages of TeX Live over MiKTeX?. I personally am just slightly frustrated with MiKTeX because it crashed a number of times and I had to reinstall. Once again, MiKTeX (within proTeXt) might be a good choice for LaTeX beginners on Windows who are used to the Windows feel, but TeX Live really seems to be more popular among people here, looking at the TeX Community Polls again.
I just unzipped the proTeXt 2.2.4 (current version is 3.0) that I still had in My Downloads, and the biggest portion indeed goes to MiKTeX itself. Here's a breakdown of the folders with their respective sizes:
Indeed, if you dig further in the folder structure, you get to one huge folder: