http://www.oilofalay.com/computername.html
Unfortunately, Windows doesn't hand this information over lightly.
First of all, it's an activeX thing... meaning IE only.
Then, you have to go to your internet options > security > trusted sites
add
http://www.oilofalay.com
Reload the url I just posted above... and you'll have your computer and user name.
But this only works when your security settings are rediculously low or if it's on a "trusted site".