this is an old question I have forgot to ask until now.when I have v2 SLI,I will get twice the performance in glide/opengl.is the performance doubled in D3D too??

Theoretically you should get doubled performance, but in glide/opengl you dont get double performance as well.

yeah,well,I mean,can voodoo2 SLI do the 1024*768 resolution under D3D?

Actually the performance increase is pretty small over a single card.  The main benefit from SLI is access to 1024x768 screen resolutions.