I would select the option to "automatically select open file technology". That way when the backup is run it will attempt to use whatever is available on the server.
Symantec Volume Snapshot Provide (VSP) and Microsoft Volume Shadow Copy Service (VSS) are both snapshot providers that will do the same job during a backup. The only noticable difference is one is provided by Microsoft and the other is provided by Veritas/Symantec. VSP is mainly used on systems that do not have VSS (Windows 2000). VSP is also the default snapshot technology Backup Exec will attempt to use.
Veritas Storage Foundation for Windows Flashsnap Option is another application that does disk based snapshots. If you have not purchased this application/service then you will not be able to use this option.
