There's been a lot of discussion about that already...

http://www.larian.com/ubbthreads/sh...&sb=5&o=&fpart=1

Personally I can advise to enter sneak mode as soon as you enter the area with the DK's. Then shoot at them with a X-bow or bow (whatever you have) and make them come to you. This way you can pick them off one by one.
If you're really patient (or have points in bow/crossbow tree already) you can try shooting, waiting for the DK to return to its original location, shooting again and so on.

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