what's the resolution of the images?
if they are pretty high rez, you can scale them to the size you need them in photoshop first, then if needed add some blur. or, you can scale them in ae in separate comps, then work with those comps in your main comp adding some blur if needed (this should work unless you need to turn on the colapse transformation/continuous rasterization option).
if you are seeing field flicker from interlace interference (you would notice this on horizonatl lines/edges on a tv/broadcast monitor), adding a little blur vertically can help. also, a photoshop action called
deflickerator from adobeevangelists.com will selectively blur areas of you image that cause interlace flicker, or judder. you would place the action in you photoshop actions folder, then load that via the photoshop actions palette, then apply it to an image.. note, for best results, the image should be the resolution that you will be using in ae.
Kevin Camp
Designer - KCPQ, KMYQ & KRCW