Question : What's a good backup?  Using Backup Exec 11d, 12.5, and 2010 (different sites)

I'm a new employee with an IT consulting firm and have been tasked with taking over the backup duties from the previous employee.  From what I gather, he did not do much homework into configuring the backups (jobs not broken into seperate jobs, wrong options set, etc) and the first thing I'm trying to do is put together a disaster recovery plan.  I'm trying to keep my recovery time objective as low as possible so now I'm wondering.... what makes a good backup?

If I wanted to restore the PDC - do I need to backup all of C: including sys state and shadow copy components etc?  Do I just need to backup sys state, c:\windows, c:\program files, and and the admin account under c:\documents and settings?  I just want to make sure that if one of the servers i've been tasked with backing up dies, I can restore it to it's previous functioning state.

User data is simple.  I just want to make sure our clients who are paying for LTO 4 tape drives, licensed copies of BE, etc - are getting what they paid for.

Any links covering this (i'm surprised I haven't found much of anything usefull yet) topic would be greatly appreciated.  It seems like more black magic than science.

Answer : What's a good backup?  Using Backup Exec 11d, 12.5, and 2010 (different sites)

In general , clean up the OS drive and do a full backup of it regularly ( once a week ), incremental dailies with system state
That should at least recover the  OS for a server, as long as there are not any programs that require data on a different drive/partition.

Some stuff requires being backed up together such as Exchange data, SQL etc.

I hope this helps !