"Regardless of genuine status, you'll still be able to get critical security updates. However, if your copy of Windows isn't genuine, you won't be able to install many updates that are exclusively for genuine Windows customers, including Microsoft Security Essentials. Microsoft strongly recommends that you get genuine Microsoft software immediately to help ensure a safer computing experience."
Seems odd that Microsoft allows any updating, for non-genuine status.
On the Linux matter, I only have a bootable DVD for Linux Mint, works very well, nice interface, easy to use.
I have no reason to believe it would be any different if I installed it to my hard drive.
I've never been asked for a password with Mint Live CD/DVDs, just boots to the Mint desktop automatically,
albeit slowly obviously - about 3 mins on my old desktop computer, Win XP Home.