Not just because of that. You still have to upload all of the pixels to the graphics card, each frame. Also, how would you scale/resize your sprite? AFAIK, common OpenGL implementations do not support such operations (I found a Google link to an HP-extension that supports scaling/resizing), so you would need to do this on the CPU.
that part is trivial. Simply create a scaling matrix for whatever scaling you need and make that your modelview matrix. =)
After that it's just a matter of drawing the polygon.