I am testing several versions of Slackware running on the Cedarview DN2800 desktop machine, and I have had great success using the MeeGo/Tizen 'adaptation-pc' kernel. With RIPLinuX, the rescue system version of Slackware, all you do is replace the RIP kernel supplied with the system with a recent MeeGo kernel and its modules, and RIP has its own fbdev_drv.so driver that works seamlessly with the new kernel.
With the Absolute Linux version of Slackware, slightly more complicated, since you need to compile fbdev_drv.so and use lxrandr to get rid of the spurious screen that the system tries to provide you with. Once initial problems out of the way, though, runs quite smoothly. Slackware 13.37 likewise runs with the MeeGo kernel and your compiled fbdev_drv.so.Note that these two systems should be started with their native kernels, then moved over to the MeeGo kernel after "first run" problems are dealt with. Main reason for ditching the conventional Slackware kernel: Doesn't run in 16:9 with kernelmodesetting, while MeeGo with fbdev does.
Typical Peacekeeper Benchmark scores with both MeeGo and the Slackware versions using the MeeGo kernel is in the 700s, althought the slitaz 4.0 distribution using their vesa driver and the 915resolution program did actually get something over 800.
If you despair of ever getting the ultimate in high-resolution mpeg4 video performance, the latest versions of google-chrome have a top-secret built-in video player that gets activated with either the Slackware mplayer plugin or the Xine plugin (!) installed and runs very large (300 megabyte tested) mpeg4 video files at full speed, complete with audio synchronization and no slowdown or dropped frames at 720p. In other words, you don't have to resort to a Sandybridge alternative to get the desired performance. Let's hope that Google continues its recent generosity in including this capability.
OK, the mplayer plugin is from the Slackware 13.37 'extra' directory, while the Xine plugin is available pre-compiled from Ubuntu sources.
Banshee, by the way, does not handle mpeg4 at all, although it appears to do fine with ogg files on this system.