Compiler installation that's easy
The nuwen distributionult of the GCC compiler includes the compiler and all necessary supporting tools and libraries as one Windows Installer. You don't need Linux emulation to use it. A similar, slightly smaller pacakage TDM MinGW build . Both are on GCC 4.5 (as of August 2010).
If you want an IDE, then Code :: Blocks also comes as a complete system. Has been greatly improved recently (July 2010) and comes with GCC 4.4.1 compiler if you want. You can also take a look at CodeLite , which is pretty easy to install as well.
Qt for Windows comes with MingW, which I find is fairly easy to use and install, and the LGPL version (free as in beer). You don't need to use any Qt libraries in your application. I'm not sure which version of GCC will be bundled with it. No licensing restrictions on the software you develop (unless you actually modify or redistribute the LGPL Qt version source code).
a source to share