Following procedure worked for me
1. Installed SL 10.6.3/10.6.4 (working both)
2. while Installing uncheck GraphicEnabler and/or any driver for VGA/Graphic
3. Check the Bootloader (I've used AsereBLN)
4. Check Ethernet driver u need
5. wait until Installation is finished, restart, changed the bootsource from DVD to HD in Bios, restart again. OSX started, then I've used Multibeast + Combo Update 10.6.6.
6. Restart again
7. Installed tonymacs nVidia Driver and restart again
8. fully working SL 10.6.6.
Had no freezes right now (after 2 hours now.)
For information: I dont play games or something, only developing apps on osx.
Thanks for this site and your work!
Kind regards and many thanks from Germany!