need Open GL graphics card

I want to port an application from SGI Unix computer to PC architecture under Linux or Windows. The question is, what card do I buy that has some of the OpenGL features that I need:

(1) transparent surfaces need alpha blending. Do all the PC cards
have that?
(2) 3D texture mapping. Do any of the cards have that?
(3) four overlay planes. All Unix SGI computers have 4 overlay
planes. Can I get that in a PC card?
(4) All SGI computers have 12 bit pseudo color visual besides 8 bit
pseudo color and 24 plane true color. Is there any graphics card with
that? This last feature I can live without but it is nice for some things.