You can't really avoid active directory with server 2003, get one and you get the other. That said though, you can also enable NT domain support so you can carry on using legacy clients with the new server.
Advantages of active directory? There are many but some of the main ones are support for multiple domains within a single administrative structure, single login for access to all resources (if set up properly), greater resilience (due to the way the active directory is replicated between the ADC machines), easier administration (again, if you set up your directory properly), greater flexibility (in terms of moves and changes), better server performance etc
For loads more on active directory have a look at
tnx bishop for the reply, do you know some links of a step by step creation of objects or implementation of AD. most of the sites i searched was more on discussing the concept of AD rather than the actual creation. i'm sorry for asking these some seems dumb questions. :oops:
Actually implementing your active directory is easy enough; you just create your container hierachy and then create objects such as users and printers inside them. Computers get created when you add them to the domain. Then thirdly you associate login scripts and/or group policy settings with the containers so they apply to the users or computers within them to give you the security and control you want.
Designing the structure, however, is key to the success of the implementation and is an area about which many expensive books have been written. Have a look at this link for a start. It's a bit long-winded but does cover the key areas fairly well.