2560x1440 swf- how can I put into browser to look good?

I have made a simply intro, that are just some photos that goest into alpha.
Because I wated also a nice bg that will be changing with these photos, I have made some hudge bg (2560x1440) and mounted these changing colors bg.
Now my problem is, that when I go to the browser, it shows me full 2560x1440 picture, and in my small browser it looks not good, means it resized my browser window, and pictures are not in the centre, but somewhere down…
So there is my question: is there any way, to “cut” this 2560x1440 dimension, but not in fla, but in a way thet the browser will be only showing size that needs, that fits its own risolution, without resizing all, only “cutting” this 2560x1440 into own size (not fit screen, when also photos will be smaller- but “cut into screen”).
Sorry for my bad launguage, trying to write it clearly, but know with my language skills it might be not easy to understand what I want to do. :alien2: