I used to be hard-core PNG until I figured it out that PNG isn't the total solution for everything. JPEG for normal stuff [be sure to use GIMP or PS to save it as a high-quality JPG or else it's crap], GIF for animated or stuff that needs basic transparency [same with JPEG; optimizing with GIMP/PS first is recommended], and PNG only when the losslessness/palette preservation is crucial and using alpha-T. Otherwise I found that PNG sometimes loads funny and chews up bandwidth [even at it's 'small' size] and so I usually try not to have a pagefull of PNGs if it can be avoided at all.
But yes, do use PNG for Soldat screens. If MS-Paint won't save PNG for you, then try downloading GIMP or Paint.net [yuck!].
