I honestly JUST installed a stripped Windows 7 custom version. I also just unistalled it. I did this three times, removing less each time because it's an absolutely terrible idea to do this if you're gaming.
I went through hell trying to figure out why Windows kept getting errors, so I would edit the installation with minor things (removing non essential functions and such) but Windows would still fail an sfc /scannow procedure. With over 2000 errors all because of how unorganized the install became, thus creating instabilities.
I even tried just removing themes, backgrounds, games, etc... still didn't run well. Even with the guide I followed online (to the dot) i would get instabilities. And it didn't even save much space... you can save just as much doing post install tweaks!