@Flashkit: you can save ~ 75% of that large spritesheet by cropping to its smalest bounding box and by removing the last 1/2 of them as they can be copy mirrored via code.
I can PM you some specific tutorials regarding this I did for the project I once PM´d you about. Its basicly using Photoshop CS3+ (video frame edit features) and some general concepts.

Maybe send me the spritesheet without the white in the background so I can give it a try