I've read that certain amiga ppc demos (like planet potion?)
don't work on the Peg because Radeons and Voodoos do not
support 15bit screendepth...can anybody confirm this?

I can confirm, that 15 Bit does not work.

Thanks for the confirmation.

Well, there are a million old and cheap
Permedia2 PCI and AGP cards out there...
some which support 15bit modes, so my
idea was to try to get some of these demos
which need 15bit to work...maybe a "rainy
day" project. :)