Okay, i've been told that there is a lot of overhead if d3d has to switch the texture for every polygon, so it would be better to pre-sort the poly's by texture.

unfortunately, this is not possible in my case, because the poly's that i draw are different each frame, so the only sorting i could do is per-frame sorting.

Im wondering if this would be better than texture switching?

One thing to remember is that when you are using partially transparent surfaces you'll have to sort your drawing so that they are drawn last anyway. Otherwise whenever an alpha blended polygon is drawn before a polygon that is directly behind it, the occluded polygon will never be drawn even though it would normally be seen.