I recently found out that in Settings > Control Panel > User Accounts it is possible to change the name of your account. However, doesn't this have implications where your shortcuts links etc, will be non-functioning as many will redirect to a user that doesn't exist (because the directory has changed)
Example: C:\Documents and Settings\John\Startup Menu will be changed to C:\Documents and Settings\IlikePinkPonies\Startup Menu and would cause all shortcuts to subsequently fail.