Cross Dissolves Between Streaming Textures

What is the most time-efficient method of dissolving between two video texture streams? I will be using 2048x1536 images, displaying in two different windows, each window with a different texture lookup of the same program. Window sizes will be different. OpenGL has so many features that support Alpha Transparency, I can think of a few different techniques. I could use:

-Multitexturing w/Texture Combiner Function
-Fragment Shader with 2 Texture Samplers
-Accumulation Buffer Operation

I appreciate your thoughts.

Forget completely accum buffer (rarely hardware accelerated, being abandonned).

Then if you have recent enough hardware (needed for speedy dissolve anyway), go straight for the modern thing : GLSL Fragment Shader with 2 Texture Samplers.
It will give you much more power to do exactly the dissolve you want.

Thanks for the tip, ZbuffeR!

Hey guys, am just begining to learn opengl.
I need to display diffrent images randomly (one after another without any key press) what can i do?