Panning/moving images across a screen

I am creating a flash site and as part of my intro i want a series of images to pan across the middle of the page in a steady motion and smooth stated with no jerks, and at a constant slow pace through out, how can i ge this to happen? Hope someone can help thank you, i have mamaneged to do it useing tweens and a lot of timeline space but the effect is not smooth and the speed of it is too quick is there a way without tweens(as it takes up mor memeory) that i can achieve this effect?

thank you