I just tested it on my netbook, an Asus Eee Pc 1008ha.
CPU: 1.6ghz Intel Atom
Graphics: Intel GMA 950 (The.. well.. suboptimal onboard-graphics chip)
The game really turns into a slide-show, even if you deactivate all special effects the game provides.
But if you limit the framerate in the options, the game turns somewhat smooth again. I find that I can play it perfectly set to 30fps.
the only real problem I had was that the options screen in itself is too big to fit the tiny resolution. Kudos for letting me choose 640x480 or 800x600, but what does it help if the option-screen itself higher than 600 pixel?
I say its definitly playable. Just not the prettiest thing.