Make a copy of your internal disk to an external Disk (.dmg file) with DiskUtility (you have to start from the CD to do that). Replace the drive, boot with BootCD choose "restore from" in DiskUtility select the .dmg file... wait... you're done.
This option looks really sweet, but i'm finding it hard to follow. Could you please repeat this step for a complete idiot (fairly new to this whole Apple biz).
Cheers.