Long story short - it's working great now, and I actually have an outstanding laptop graphics card.
The only thing I miss right now is the... battery life. On the X3100 with WiFi and Bluetooth disabled, and the screen dimmed to the minimum level I got about 7.5 hours from my original 8-cell battery. Right now, with the Nvidia Quadro FX 570M is only about 3.5 hours (according to the Power Manager, from my experience it's more like 3h).
I'm writing this so this is a tip for people who are considering the discrete graphics. So if you need battery life, the Quadro FX would be a real deal breaker for some. Fortunately I don't need as much battery life as I had (I don't travel that much), but it was nice to have (you never know when you might need it)
Other thing that I noticed is that my temperatures got significantly higher. On the X3100 I never hit the 70*C when stress-testing. Right now, without my undervolt RMClock settings I hit as high as 90*C after 10 hours of Orthos heating (fortunately no real app does that kind of stress, as I tried encoding a movie which lasted for a couple of hours and only got to about 80*C).



