In the past I have only used Windows 2003 Server to run a small computer lab. Active Domain was simple enough to understand for a person that had never dealt with domain servers before. I am in charge of a new computer lab now and have been giving thought to using a linux server instead of a resource-hungry and glitchy Windows 2003 server. I have never really used linux before, so I know next to nothing about it.

Which distro and what programs within linux are crucial for setting up a basic server that does the following:
- maintains a list of accounts that are allowed to log into the computer lab systems (Vista, XP and Linux systems, some dual-booting)
- have two different labs with different account lists
- apply group security policies and scripts (allow/deny access to certain Windows features, accounts designated as admin or limited, automatically check and add network printer to their account, provide home folder on server where their settings/desktop/mydocuments are stored automatically)

Other server features I will probably implement as I did with the old Windows 2003 server:
- FTP server that uses account list username/passwords so members can access their files over the internet
- Web/PHP server
- Network print server
- Network file server
- DC++ server

There are quite a few linux users living here that work with linux/unix servers professionally, but they are never around to answer any questions, let alone help me build a server.

are you sure you need a domain? the closest you can get to AD functionality with linux would be by using OpenLDAP, but it is not a trivial task to set it up.

anyhow, ftp, http, print, nfs, smb services are not distro dependant, they can run on any distro.

but you need to understand linux is not windows, and the way you do things there is completely different