When you say "everything is centralized", what do you mean? It can mean many things.
- Centralized authentication for user logins would require something like LDAP or NIS.
- Centralized DNS, would require using DNS bind.
- Centralized Linux file sharing would require NFS.
- Centralized use of a Linux server for Windows XP / Vista file shares and logins would require Linux Samba.
- Centralized online web based documentation could mean the use of a Wiki.
Which one do you want to start with? Let us know and we'll point you to the right resources and provide advice.