alex, i don't really remember, sorry. i know (or at least "as far as i know") that psds are compressed on save. i think i read somewhere/somewhen that that is a lzw compression. what kind of lzw compression it is or how good is it... sorry, can't remember. but if you compare uncompressed tifs with psds you'll see that psd is smaller. you are right concerning no alpha in jpgs. i also proposed jpgs because older software can't read pngs. you would most likely win your bet, but loose layers :) photoshop 5.5 and lower can read layered tifs but it interprets them as one (flatened) layer. and that isn't a solution for given problem, is it? :)