mobo for a SS51G case

its a long story

i had a good deal on a few Shuttle mobo's, so i brought them

so i now only needed a SHuttle case, so on ebayer i see some guy selling them for 30 quid

it arrives today

i open it up to fit the mobo and cpu (all fitted in a different case at the moment) only to find the Shuttle MK35N mobo is massive compared to the Shuttle SS51G case :(

so any1 know where i can buy a mobo to fit the case, i have the cpu and memory etc (cpu is a old Duron 700, the box is only for a MP3 player sat in the spare room) i dont mind gettting a mobo / cpu bundle, if cheap enough

cheers
matt