Internet Guest Account

I am very new to IIS and Windows 2003 server. I am installing a UBB Messageboard that requires that Internet Guest Account be the default for web visitors to the messageboard area of the website. I have checked the installed users and I can see what I assume is the relevant account below:

NAME: IUSR_WINSERVER2003
FULL NAME: Internet Guest Account
DESCRIPTION: Built-In Account for Anonymous Access to Internet Information Services

Is this the default guest account? I am being prompted for a userbame and password when I try to access this particular directory of the messageboard. I have followed the instructions to allow permissions on this folder to the guest account above - but it still prompts for a username and password.

Should it being doing this? Am I doing somwthing wrong?
Any help much appreciated.

thx

jeff (barely sane at this point)

I'm not up on IIS6, but for previous versions of IIS the IUSR_computername user account is the account used by the web server. If there is any call to any folder, html file, asp file, js, css, image or any other link that doesn't allow the IUSR_computername account then IIS prompts for a windows login for some account that does have permission.

If the login is successful, IIS will continue to impersonate the logged in user.

on IIS 6.0 the IUSR_XXX account is dramatically low-privileged, so ANY function but reading static content (.html, .jpg, .bmp) is disabled by default.
Take a tour at your permission settings to enable it.