Well, it helps if you're clearer with your questions. To my knowledge, there is no such thing as "Textured Preview" in WED. If you mean the 3D view window, then I'd suggest changing the Video-out dll used for the 3D view. To change it, click File->Preferences then click the open folder button near the bottom in the Main tab. Try gxl2basedx9.dll or gxl2basedx9a.dll.

FixxeR