http://bugs.winehq.org/show_bug.cgi?id=10557
--- Comment #10 from Stefan Dösinger stefandoesinger@gmx.at 2007-11-27 07:55:53 --- Thanks for confirming that this fix helps on gf8 cards as well.
Portal has broken colors in dxlevel 90 and 95, that is indeed a different issue. Patches for that should come as well, propably they are in by the next snapshot on friday. dxlevel 90/95 on all Source engine based games are slow due to constant texture reloading. This is a bit more tricky and I do not have a fix yet, so for now dxlevel 81 is recommended for all of them.