Depends on what you're using ? Windows Loader or Microsoft Toolkit aren't cracks, it's activation (no system files or reg entries modified). Using those can be considered safe .
If you have used, Windows Loader or MTK, you can trust them by closing your eyes. They're all used by millions of peoples around the world wide.
I saw two file from the "tak manager". The user is empty. I'm afraid of someone will steal my password.
Looks legit to me. What files do you mean in Task Manager? The Loader has no files/services running . The trick is done during boot process.