Well, for starters i'm pretty sure nouveau is enabled by default, I prefer to use the latest stable drivers from Nvidia, usually has (recommended) written next to it found in the Driver Manager program found on LinuxMint Petra releases. One click and it installs and a reboot is required to remove Nouveau.
It really is that simple.
I'm not able to give more info other than that, i'm sure the likes of bad apples, gordon and others can give you more details.
Personally, I'd go back to LinuxMint, Install it, make an image of your drive and try as i suggested above, if it fails just recover the image and try again. But really it takes less clicks to download and install the latest stable driver in Linux than in Windows so you really shouldn't have ANY issues.
