Onegai Sister (part 1) manga trouble

Hi, I just tried saving the Onegai Sister pics individually with my PSP however I think the format might be screwed up because my PSP has other PNG format images and they display. Is there anyway for someone to look into it? Also if by chance there is nothing wrong could someone on the site reformat them to JPG? I've always been curious why there are lots of mangas in JPG format but every once in awhile there will be one in PNG, isn't JPG better?
Anyways I would just save the images on a computer then resave them as JPG format with photo shop but unfortunately I don't currently own a PC and all my web browsing is done via nintendo Wii and all my media saving (pics,movies,music) is done with my psp so between these 2 I have a half ass experience of a computer LOL. :lol:

Ok I did some research and found out that png is actually a better format for cartoon stuff, better blacks, text, etc.

Also I still have no reply to this topic, not counting my own, did I post in the proper area or should I post in the feedback & suggestions area?