USe AD its easier
Sorry to be pedantic
but its Lightweight Directory Access Protocol. MSs Active Directory is a good example of this, have you researched this avenue? You'd need to invest in a Win Server 2003 license, but I think the benefits would far out weigh the costs.
I think the MS solution is much more accessible than current linux distros, simply cos it does everything for you. Don't get me wrong I'm a great fan of linux (Fedora Core rules). BUt MS has wizards for everything; DNS setup as mentioned earlier (an integral part of any AD domain), DHCP and the entire TCP/IP protocol. As well as wizards for settting up app servers and published shares. Of course it may seem you're putting all your eggs in one basket but there are facilities builtin to fail over to a BDC(backup domain controller) should you're pdc (Primary Domain Controller) die.
You'll be able to manage user accounts, computer accounts and share accesss all from one console. From within AD you can define roles and lock down each workstation according to assigned roles. If you're really adventurous you can loook at login scripts, which would automatically map your users to the appropriate file/print shares. This would mean that you would never have to leave your desk ( barring network or HW failures). I realise this all sounds a bit daunting at the moment. BUt give it a months solid research just trawling the net, and it#ll definitley pay off.
In the short term the reason why your users are getting logged of when you rdp to is cos they're runnning XP, you can set up a terminal server in 2003 wherby multiple users can rdp to the same box, but XP doesn't suport this featrure ( I think).
Anyway if you want to remotely control a pc aacross a network have a look at VNC (Virtual Network COnnection), its quite similar to remote desktop, but you can see the same desktop as the user sat in front of the workstation, and remotely control it. The best thing is its free!
Hope that was at least slightly helpful