The witcher EE actually works fine, there seem to be some problems with upgrading from regular edition, I advise seeking help on official Witchers forums and support.
This howto was tested on wine 1.1.5 version on PC with GF800GTS card.
Using this registery keys for Direct3D gives 100% performance boost to
Direct Draw Renderer: opengl
Also there was need to put d3dx9_36.dll to the game dir , else it would
IMPORTANT- There is a strange bug , when skipping intro, when the wolf
medalion appears DO NOT press ESC to skip it, the game hangs for me,
after you wait few secons the main menu appears and you can play the
Do not try to install any DirectX stuff or ither unecessary libraries this will mess your wine prefix up.
Please read the comments how to emulate .NET if you dont own the EE edition and you just want to upgrade regular witcher.