How firm are The Witcher 2's minimum required specs?

According to TotalPCGaming.com, Steam, and the official site, The Witcher 2 requires at least a Radeon HD 3850. How firm is this requirement? Has anyone managed to play with a lesser card? (Bonus points if you can talk about the other required specs as well.)

I ask because one of my PCs has a Radeon HD 3650* (later rebranded 4570/4580), and I'd prefer to use it if possible. I've also noticed that nowadays "minimum specs" are generally the specs required to have everything at medium detail and the like, rather than an actual hard minimum.

_{* The 3650 is actually superior in some respects, such as having twice the RAM. Memory bandwidth is a bit over half, though.}

The answer: Pretty firm. The game is playable on the lowest settings, but pretty choppy. Not an enjoyable experience, but at least it's doable. The CPU requirements seem to be basically the same -- you can run it on a fast single-core, but not well.