Ibook G3 Logic Board Help

[KevinRichmon103]

Ok, i have a Ibook G3 duel usb that was sopposed to get a new logic board, but it didnt. and its over three years old and i have no apple planon it. so basically i dont wanna pay to send it in and i plan on fixing itmyself. my plan is to buy a new mother board off of ebay and install in myself. my question is my ibook is 500 mhz, would i be able to get a 700 or 800 mhz ibook g3 logic board and install that? or would i have problems with over heating, and would everything work out okay? would it fit? or does anyone know any other way to fix the stupid logic board problem.

thanx