adsiedit.exe allows you to click your way through the AD directory tree and view and edit attributes, in short. It's pretty handy for quickly getting the dn of an object when you're not entirely sure of the directory structure to begin with. It's all rather self-explanatory and clicky friendly:
We've a problem whereby Entourage cannot access the GAL, since it can't find an LDAP server, with Entourage configured assuming the LDAP server is the same box as the DC for the site (which is also the Exchange box).
By default, MS puts the LDAP server for a site on the same machine as the DNS server, though they're not very clear about this.
To find out the settings for a particular site, on a Windows box hold down