Ultimate Boot CD

how do i know its the correct size and how would i know its detect? would it just say HD detected? Which BIOS option from UBCD do you suggest? Im kinda new to this. Ive run a diagnosis from the computers setup and I always get a error message everytime i get to the Hard Drive, abut everything else s...

I need help and fast. My computer had a message saying that there was a disk error at the beginning at the start up so i went into UBCD and did a disk wipe from PartedMagic. Now everytime i startup the computer it tells me no operating system found. What do i do now?? Please Help!