Go to the ut2004.ini file and look for:
Engine.Engine]
RenderDevice=D3DDrv.D3DRenderDevice
;RenderDevice=D3D9Drv.D3D9RenderDevice
;RenderDevice=Engine.NullRenderDevice
;RenderDevice=OpenGLDrv.OpenGLRenderDevice
;RenderDevice=PixoDrv.PixoRenderDevice
remove the ; to the OpenGL line and add it to the D3DDrv line.
I tried it tho and it ran like crap
