I have been for some time with Gentoo, but recently I bought an old Acer Travelmate 4150. The exactly problem is explained here:
http://forums.gentoo.org/viewtopic-t-356400-highlight-travelmate+4150.html
It seems to exist a solution, and I was hoping that with 2007.0 the problem was solved, but it wasn't. So, looking at the explained solution, just a copuple of lines added, I would like to have this implemented in 2008.0. Now, it is almost impossible to install Gentoo on my Acer, it is so slowly that it can desesperate yourself.
I have tried Ubuntu 7.10 and the problem was solved with them. With Ubuntu 7.10 DMA is active. From Gentoo there is no way to activate DMA without the patch.
Thanks!