SHOW YOUR NAME IN VISTAS TASKBAR
Well here's a tip, which may interest some; esp the younger set. You can
customize the alphabets appearing after the time numerals in the
taskbar. Put your name if you wish ! Click Start > Control Panel >
Regional and Language Options > Customize Button > Time tab.
Here, change both the AM and PM letters to any name you wish. Click
Apply > OK.

You can always reset the settings to default, by simply clicking on the
reset button or by changing it back manually to AM and PM.