Changing "admin" name

MacMall installed Parallels and Win 7 Pro.

I changed the admin user name to DaveHyatt

Then I migrated my old computer/files to my new Mac. Here the old Admin name was/is David Hyatt. This admin cannot see Parallels etc.

In order to use Parallels I have to change users which takes me completely away from all my files etc. I might as well be using boot camp.

How do I change the DaveHyatt admin name to David Hyatt so everything is all in one place? Or what should I do otherwise?

OH, MacMall is zero help.

Thanks,
Dave