There is no easy way to find a host header in IIS. Unless you think clicking on each site is easy. I have found it difficult to find them in large installations. I wrote a script that will go through each site on the server and look at the host headers and then if found it will print the Site comment. You then use the site comment to find the main site in the MMC.
Here is the script.
I was put in charge of a filer migration from a old netapp f810 to a new netapp 3040 cluster. One of the systems we have that used the netapp backend was a web cluster running MS Windows 2003. When it was first built it was using a cifs shares by system name (ie: \\f810.
Bulk IIS path change script: Link
Bulk Active Directory change script: Link