Changing the user name....

Loggin' in!

Can't you just log in from the main page with your correct username??
You may have to disable "cookies" or clear them to do so!

Clear all the cookies from your internet files and then reload DR1, you will have to register again, do so using a new game.
Tools, Internet Options, Delete Cookies, and Delete Files
if you are using Internet Explorer 6.
If using a browser less than IE 6 go to C:\windows\cookies and manually delete them or just the ones that say DR1, but be careful.

It's very easy...

At the bottom right of the main message board page is a link called *** Clear Cookies *** click on this and you should then be able to log into the board with your username and password.

If your on another persons machine, I would not advise clearing ALL cookies. Maybe they have cookies on their machine they need, electronic banking, various web sites etc.