On the mention of "transferring sites", one more note ....
If you are transferring between any of these combination, you are likely going to run into serious problems if you don't correct for the permission, ownership, and htaccess command differences:
DSO server <-> SuPHP server
DSO server <-> FCGI server
DSO server <-> phpSuExec server
CGI (non-suexec) <-> SuPHP / FCGI / or phpSuExec (rare)
Generally speaking, you are usually okay changing between this:
SuPHP server <-> FCGI server
If moving a site away from a location that was originally DSO based, you must eliminate all '777' permissions, make all file and folders owned by the user, and remove all 'php_flag' and 'php_value' commands from .htaccess or you will run into Error 500 page problems.
In the reverse of that, getting a sit from a non-DSO system and moving it to a server that is DSO based (you are insane doing that
) then you would need to make sure that files that must be writable are set to 666 or looser and any scripts running tighter suexec style permissions (600 for example) would have to be loosened to 644 else you may again run into problems being able to view your web site.