CdrCargil

I tried to replace my MB because my old one went tits up. I read that I could set to bios to boot to the cdrom and WINXP would redetect the MB and all that. I exited the BIOS and rebooted. It didnt boot to the CDrom WINXP cd. It tried to boot to the OS on the HD. I got a vague WINXP error. I tried to boot to floppy and when it checks the boot record and says ok then it just sits there doing nothing. I cant format, i cant fdisk I cant do anything. Any advice?