User name administration- Vista Home Premium

Received my computer back yesterday from HP with reinstalled clean version
of Vista Home Premium.

It came back with a user name of 'test'.

I attempted to change the name to my name "Bob Lafayette" and the user name
in task manager under user shows up as "BOBLAFAYETTE\test".

In System Information the user name shows as BOBLAFAYETTE\test

In user profiles the administrator shows as Bob Lafayette.

The computer name shows as "BobLafayette."
Computer description shows as "Bob's Computer."

How can I amend the user name in task manager to reflect solely
"BobLafayette"? Without the "test"?

Please use extreme details.

Cordially,
Robert