MedievalFantasy: SO I just downloaded Patcher_ATARI (assuming that's patch 0). The game's already uninstalled. So now do I just put the discs in, let it install until the activation key window pops up, then close it and click the Patcher_ATARI, then the patch_1.1, then 1.2? Because earlier today I closed it on the activation key window, and went to My Documents in The Witcher 2 folder (not Witcher 2 folder, but THE Witcher 2) and clicked the Patcher_ATARI thing in the folder and it just patched me to 1.3. So I don't know how this works.
Sorry that our instructions have been confusing; I think it's a result of the fact that most of us do NOT have the boxed version, but rather the GOG version, so we're not sure about the process of removing the DRM after installation.
I would recommend first following the advice that Kleetus gave, which does not require you to disconnect from the internet. If that works, then it's probably the easiest way to do it.
I would also like to add that you can check the version number of the game if you are uncertain how many patches have been applied. Go to the folder where you installed the game and find witcher2.exe (I think this is simply in the install folder but it might be in a subfolder). Right-click it and go to properties, and then somewhere in the window that pops up you should see a version number.
If you just want to find out whether you have patch 1.3 installed or not, you can check it in-game by equipping some bombs, daggers or traps to your "pockets" in the inventory, and then seeing if it displays how many of them you have. This feature was added in 1.3 so if the numbers show up then you're 1.3, if they don't then you're running one of the previous versions.
Also, yes I did forget to tell you to back up your savegames earlier, sorry! I hope you didn't lose too much progress.
EDIT:
Another thing you should do after you install the game is try running it right away without applying ANY patches, and see if your framerate problems are gone. Then apply patches 1.1 and 1.2 and check again to make sure it's still working correctly. If you are afraid that the game will try to auto-patch to version 1.3, then you can try running the game directly from the install folder by running witcher2.exe. In that case you would not use the launcher to start the game.