I believe you can change the name, but is only cosmetic, but may serve your purpose.
1) Start> Control Panel
2) Click User Accounts (If you do not see this option, click View by: Small icons).
3) Click Change your account name to change the account you are logged in with. Or click Manage another account to change another accounts name
4) Type the new name for the account, then click Change Name
You cannot change the actual name without creating a new account and transfering everything over. That can be done if you desire. A Guy