the name you give your computer shoulld not affect your email address as its only used to identify it on a network i believe.
have a look in start/control panel/performance and maintenance/system/computer name
here you can change the name and computer description.
im thinking you may need to set up a new .net passport email address as above you email should not be affected by the computer description or name.
i may well be very wrong just guessing sorry.