how can i cancel the "polish voice-overs" download?

With 1.1 installed, I made this same mistake, and it fixed itself by simply exiting the Launcher and re-opening it.

If that doesn't work for you, you could try deleting the Registry entries at:

HKEY_CURRENT_USER\Software\CD Projekt RED\The Witcher 2\Downloads

http://www.gog.com/en/forum/the_witcher_2/common_issues_and_possible_solutions_read_before_posting

Look for "DLC"

To install pre-order bonus:
http://www.en.thewitcher.com/community/entry/34/

Make sure you are patched.

There is also a registry tweak if you search the forum a bit.

ok, it worked, but now i can't install the DLC, the game is patched, they are installed, but i cannot enable it via launcher! :(

The DLC is installed (assuming Troll and if you went ahead and picked up all the other pre-order) regardless of whether a green arrow is next to it or not.

Also, everything about the "Downloadable content" button on the Launcher is broken. JUST DON'T USE IT. IGNORE IT. Words from CPR's mouth. :p

The "Downloadable content" option in the Game Launcher does not work properly, please don't use it.

http://www.en.thewitcher.com/community/entry/39/