and some advice from me, for one and all: I know auto installers are cute and efficient and easy.
but man...just say "NO".
"Install" with your auto-installer first to an empty folder somewhere, and INSPECT the contents at least before blindly unleashing it onto your unsuspecting game.
And for crying out loud, dont go installing things into your main game install after downloading them. Have a "test" install that you can afford to break. I know a shitload more about mods than many, and even I NEVER INSTALL STUFF INTO MY GAME ON FAITH. I inspect, and I test, and therefore, I almost never have any shit.
And as Frankiek says, and I have also said many times, yes, coexsistent installs is very possible, but if you do not know enough to manage it when it gets tricky, please, dont do it. Just have an extra install or two.
Bottom line is, treat your main game install like you would treat your ass. At least look new things over and pick off the splinters, and test them on your cellmate, before going ahead and ramming them up in there.