Large scale OSX Server deployment advice

I’m an Apple Service Technician recently given the additional duties of managing XServes at multiple sites. I’ve got a plan in mind, but would love some advice from those more experienced.

OK, first of all the school system has 29 locations each connected via T1s to a central site. 19 of the schools use OSX, but 8 will have XP and servers running Server 2003. The other 2 sites are non-student. Each site has it’s own separate network (ie 192.168.1.1 for site 1, 192.168.2.1 for 2, etc) with only the central location having a live connection.

I have 24 G5 XServes and need the following services: mail, DNS, DHCP, User Home Directories, and hopefully some sort of integration with Active Directory. I already have mail running on an older XServe, that is working fine but slow, and will be moving or setting up from scratch mail on a new XServe. Mail is currently being used by about 3000 users, but more may be added in the next year or so, and my user database is going to be large, probably around 17,000 or so.

My initial plan is to place 5 servers at the central building and distribute the other 19 between the schools. At the main site I would have a Server 2003 box with AD as a PDC and also run:
1: LDAP Master
2: Mail
3: DNS
4: User Home Folders/DHCP for local site
5: Backup? Spare server in case of hardware failure?

At the 19 schools I would then run a local DHCP server, local user directories, and LDAP replica.

Does this sound like a feasible idea? What would you do differently. I’ve got some time for planning and want to make this as easy to manage and keep running as possible, while allowing me to move users between locations and add new users quickly and easily. I would love to be able to fully integrate OD and AD and not have to worry about duplicating data between the two.

thanks for the help
Britt