Next release of Backup Exec, BE 2010 (if that's the final name) will do backups of vSphere guests using new VMware Storage Apis, until new version you have to use VCB.
BE 2010 AVVI with ESX 4 (vSphere) does not require anything to be installed on either the Virtual Center Server or ESX host server. However to do application level GRT you will need to install the RAWS software inside your virtual machines.