Ah to hell with it, the game was installed on my primary HDD anyway when I actually wanted it on my secondary... I guess a full reinstall it is then.

Sure, I had it already too downloading just in case (and had already the GOG version before too), but it will take quite a lot of time with my connection.

it's file part 1 and 2, NOT part 0 and 1.

You just need to redownload part2 from the link above. I found that out when I tried to delete the setup files during the error message and could delete everything except for part2, which was already in use by the installer.

Patch installed, game works fine!

Here's exactly what I did, for anyone still having trouble:

1. Went to http://en.thewitcher.com/ee_manual and downloaded Part 0, Part 1, Part 2
2. Moved them to the C:\Downloads folder (default location the installer uses)
3. Went down the page to "Enhanced Edition English Language Pack - 5 links" and downloaded 'Part 1'.
4. Moved 'Part 1' to C:\Downloads
5. Ran TW2EE_Patch.exe

Differences noticed so far: 'Enhanced Edition' has been added underneath The Witcher 2 logo on the main menu screen, in the Extras menu there's an option to watch the new cinematic, and the new lighting tweaks are in - better sunbeams and better light on Geralt's face. Also there's a very welcome addition to the options menu in the launcher, now you can disable the DLC bonus weapons and armour.

cool yeh downloaded part 2 as well and installer appears to be working now! thanks

Only replaced Part2 and installer works so far...thanks for tips everyone!

Replaced 2 and it works now, thanks for the tip.

Thanks for the guide! Hopefully this works for you. I was having the exact same issue but chose just to fully redownload and reinstall the game as I wasn't sure how long it would take for someone to work out a fix/if the problem was fixable.

Looks like if I hadn't been lazy and had just redownloaded the language files, I might already be done. Oh well, hope it works out for you at least!

Same problem here. Downloaded part2 and replaced in download location folder. Worked ok, installing now. Thanks for the help!

Witcher2/downloads or just c:/downloads?

C:\Downloads, if you're using the auto downloader it should have that as its default, but really it doesn't matter where if you're choosing to do things manually since all you need to do is run the installer in the same folder as all the parts.

Now it's asking me where the rest of the patch is. I pre-downloaded it, but I dont know where the files are. I re-ran the patch downloader but it's telling me I already downloaded it.

This is indeed the solution. But only part 1 and 2 need replacing.