Clean install of vista Business from upgrade

I have a problem in that i installed Vista Business on a new HD and have moved all files etc to new HD and now would like to remove old smaller drive. But the new will not Boot. I seem to have missed something as it needs the old operating system to boot. there must be a way to move the NTLDR to the new disk but if there is i have forgotten how to do it. May be someone out there can help. thanx Jack