The Dutch Windows XP contains a bug: when you click Remove, nothing happens......
But
I realy suggest you to not delete all those files/directories just like that if you don't know what those directories and files EXACTLY are... This can cause many troubles and side-effects.... Be very carefull in what you delete and stay in the directory of your windows useraccount, don't delete any other credential....
In other words, searching your HD for those files is a very bad idea. Just go directly to the correct directory (for XP):
C:\Documents and Settings\your windows username\Application Data\Microsoft\Credentials
and maybe also:
C:\Documents and Settings\your windows username\Local Settings\Application Data\Microsoft\Credentials
And there delete the subfolders. But do not delete anything else in another directory!!!
After that, reboot...
Also, there is a tool to disable (and enable) the credentials, so that they are not saved anymore:
http://www.customizeyourmsn.com/?msn=downloads&id=405
all this tool does is this:
http://www.winguides.com/registry/display.php/1286/