Parallels Installation Transparency on my Mac

Hi everyone,

I would like to purchase Parallels, it seems to be a great product.
But before, I am very concerned on the installation transparency. By this, I mean I want the least invasive installation possible.

I don't want my Mac system to be messed at all, don't want to have weird settings like "shared with Windows" or I don't know why, don't want ghost users in the Mac system or anything that kind, if you see what I mean.
I don't want my files present on my Mac to be altered (Windows files can be different from Mac files), etc.

Therefore, I know there's a lot of people here running Parallels for ages now, and I would like to know if the installation is invasive or not at all?
As far as I know, a VirtualBox installation is not invasive at all. All the virtual system stays into the software, folders are "shared" by mounting them (and not adding weird settings to them). I didn't see any other intrusive stuff about VB before either anyway.
Is it the same for Parallels?

I figured out I'll use my Parallels installation as "Use as PC" too, to have a completely separate system.
I basically want a Windows installation that doesn't alter *at all* my Mac installation. If it does, I'd like to know what's altered precisely.

Thanks and regards
Xavier