Supporting /maintaining Web Host servers

We have a new client – a small web hosting company who has 5 servers in a mixed environment. They are NT and 2000 servers.

I’m looking for advice on the types of support and maintennce issues we should especially focus on when maintaining web hosting servers.

Initial thouhgts include:

– Power Managment
– Backup
– Security
– Redundancy

Any information or resources relating to these and other issues focusing on this environment would be grately appreciated.