Thanks HYBR|D,

I have come up with my list, short but needs improvement.

Inventory (Clients, Server, Peripheral, Printer, Fax, Photocopier, PBX, Phones)
Documentation (Network Diagram, Manuals)
Servers (Mail, Active Directory, DNS, DHCP, Print / File)
Clients (operating system, software packages)
File Permissions
Which services are running on which machine
Lan IP Address mappings
Internal Extension mapping for PBX System / External Connections
Password for all the systems (Network equipment, Firewall, Clients, Servers, PBX)
Network Topology
How the clients access MS Office Suite (publishing)
Firewall Configuration / ACL /
How the backups are made, frequency, medium, how the servers / clients / PBX are backedup
Support Contracts (Printers, Peripherals)
Supplier Contacts / preferred suppliers
If you are unable to solve any problem then what do you do
Do we deal with mobile devices
Are there any change control / management procedures
Are there any VPN connections or any one connects remotely to companys network

Please feel free to make additions and comments welcome.

Thanks