Best solution to back up Citrix Xen Server

Hello,

I am wondering what the best solution would be for the following:

I have on Citrix Xen Server host that has 7 virtual machines on it.  I am currently using PHD Virtual to back this up to a NAS.  I am looking to move to different software for the backups.  One of the virtual machines is running SQL and one is running AD and DNS.  There is also one physical server that has AD, DNS, and DHCP on it that i would also like to back up in the same solution.  What i was curious about is what is the best way to back all of this up?  Is it Back Up Exec or System Restore?  Or would neither work?  I am looking for something that will back up to the existng NAS and allow for item level restores as well as fast restores of full VM's if ever needed.

Second question is, assuming one of the two products will work is it best practice to install it on its own server or could it be installed on teh physical that is existing with AD, DNS and DHCP?  I am assuming its own server and that is what i would shoot for, but for the sake of saving money i like to know my options.

Thank you for your assistance.