Renaming accounts is difficult in Windows.
If you want every last aspect of the account to be renamed, you're better off creating a new user with the proper name, transferring files and settings, then removing the old username.
The reason is that when you create a user (for example.
Owner), that user gets its own Security Objects, file system objects (C:\Users\Owner, for example), and files will rely on certain locations. If you rename a system folder (i.e.
C:\Win7), programs and shortcuts will cease to work! There are too many internals that are relying on your account name for a FULL rename to work.
For small cosmetic changes (i.e.
Will), if you can live with just the look, it's fine to rename the account. The files will stay pointing to a user called
Wil, but you'll know who that is.
If you want the cosmetic change (i.e.
Canadian Luke ->
Luke Skywalker), you can execute (as the user or an Administrator) the following command:
NET USER canadianluke /FULLNAME:"Luke Skywalker"