I landed up aborting the Mandriva install due to these problems. I stayed up all night and reinstalled Debian. I don't know if you remember from before, but I had this same postfix problem with Debian.
Well, I had some luck reinstalling Debian. I have ISPConfig running on it as well as postfix. Everything went flawlessly!
All I have to do now is move the data to the new hd. I am just going to recreate my websites in ISPConfig just to keep it clean. I only have 4 hosted currently so it shouldn't be a big deal. Then I can move the site files over as required.