[SaintDog]

Seperating the images & attachments from the static PHP files to an external server would be doing just that, however, remaining on an Apache based system.

The static files themselves do not force a load on the server, however utilizing and storing the attachments to the database or by using the file system does when there is such high usage to these areas of the community.

Offsetting the load of the attachments and images specifically to another server will reduce the load since a great deal of the activity is there.

This is not so much for your average community with posts, threads and users online, it's for an approach using vBulletin more as a CMS and download-specific tool.