Hello Gianfranco,
While I can find laptops that are mostly Gnu/Linux compatible, it is
hard to find one that not only lets me run Gnu/Linux but also has full
3D functionality.
About a month ago, my requirements almost exactly the same as yours! I won't say that I have done extensive research in the market. But now I am happy to own IBM Thinkpad R51. Hardware acceleration works perfectly with GNU/Linux on that model. It has i855 chipset with Intel extreme graphics 2 graphics. I am running Fedora Core 3 on it. Even Redhat Linux 9 works fine with hardware acceleration. Initially i had tried installing FC3 on IBM's Thinkpad R52. I tried a lot, but couldn't get hardware acceleration working with it. Finally, i had to be satisfied with R51. The graphics of R51 supports OpenGL version 1.3, where as GMA 900 graphics of R52 supports OpenGL version 1.4. There are some other goodies with GMA 900 too.
BTW, I am from India.