I flipped through My Best Games by Karpov, and it looked like he used the QGD and Nimzo-Indian against d4 quite a bit. The games in that book against c4 were almost exclusively Karpov playing e5.
Your best bet might be to track down a copy of this book. http://www.amazon.com/Opening-Black-According-Karpov-Repertoire/dp/9548782162/ref=sr_1_1?ie=UTF8&qid=1318203278&sr=8-1
I am trying to build an opening repertoire based around Anatoly Karpov. I know that he is famous for the Caro-Kann, but what were his other top openings? I am looking for his most common response against 1. d4 and 1. c4, in addition to his systems as white. I definitely want 1. d4 as white.