I installed the new drivers and switched to low, then back to high; it froze one single time since then, but after that no more. I hope it stopped crashing once and for all; would be the first time a driver update helped me, though.
So far I've progressed until the beginning of Chapter 1. I had to repeat the prologue which made that all a bit longer
I imported my Witcher 1 savegame (fun fact: neither manual nor game guide lost any word about importing savegames, I found that on the www) and I think I got better starting gear thanks to that. The first time I played on normal difficulty, just as Witcher 1, but I couldn't stand a chance. During the prologue, I died about a dozen times. The reason is that I didn't know how to how to switch swords, when dodging is possible, how to aim at enemies etc. These things are mentioned in the tutorial, but the messages pop up right during the action and they're so small and unsalient that they're almost unreadable and get neglected. I had a girl read from the manual to me instead (yes, that sounds weird, I'll have to explain myself on toast). But that observation is (unfortunately) in line with the rest of the GUI and handling: it's just horrible. It took a couple of minutes until I figured out how I could find and use the meditation menu; CD project, in all honesty, should reeeeally consider a course in user-centered design or cognitive ergonomics; The Witcher 2 ruthlessly neglects all guidelines and standards of ergonomics and usability that might have ever been produced. Though that's an achievement in its own right

So after I had finished the prologue, I started over with easy difficulty. This time I figured out how to brawl well and now it has become too easy xD But I'm not going to do it a third time.
Story, Characters and Dialogue are excelling on the other hand. Long time gone since I have seen a similar performance - that similar performance might have been The Witcher 1. Mass Effect, Dragon Age and Fahrenheit come close, but it's not the same: the Witcher 2 people are swearing, hating, loving, joking, fapping and betraying. And bragging about their balls. In contrast to many movies, this makes them more believable. Also the places and the atmosphere is unique. It feels very real, dense because it tries to depict people in both their awesomeness and awefulness. A good example is the beginning of act 1 imo: you meet the guard captain of a small town, and while you're arguing with him, he walks across a gallow and kicks open a trap door, laughing as the girl falls through it and dies and then continues arguing, "just like that". And you have to just watch because this is none of your business and besides, there's much worse happening any second. Gives goosebumbs.
IMO until now Witcher 2 is a very worthy sequel to Witcher 1. I can't think of a reason not to want that game, other than that you hate everything except shooters.