Server Migration W2K to Linux

Hi All,

I'm looking for some advise in migrating a small SOHO network from a
Doze backend (Win 2K with AD) to a Linux one.

In brief my client has been running a 2K box since 1999 until now with
very little problems, only one was running out of HD space on user
drive.  They have a nice new server ready to go, but do not want to pay
for Doze 2K3, as all the server dose is domain auth and file and print
sharing.  Front end PCs are a mix of Linux (FC 4 & 5) and Doze XP,
(Needed for some apps)

So here is my list
Needs:-
1. Domain Controller (if I can migrate users from AD great if not only
small user base, never done this before)
2. File & Print sharing (my SaMBa knowledge is up to this)
3. No noticeable change for end users

Wish List:-
1. Exchange style shared address book & calenders
2. Centrally monitored Virus Control (Currently using Symantec Corporate
Edition)

Cheers,
Chris