Hello,

What you propose to do is change your computing paradigm all over, and this will take some thought.

NT DOMAIN CONTROLLER -- Ok, so you have an NT4 domain at your location. I assume that you have some Windows machines on the network too. Are you planning on migrating those to linux desktops too? If so, you can have a central LDAP based authentication scheme. If this computer is also doing file sharing services, then Linux will be able to mimic all of that too. With Samba, you might even be able to make it a Domain Controller (at least to Windows clients).

EXCHANGE 5.5 If you are looking for pure email, a POP3 server and sendmail will work for you. If you want calendaring, then you will need to search out some other packages. There is support out there for a palm-like calendaring program out there, but I have not found a groupware thing yet for linux. then again, I have not looked too hard. But simple email (POP3 or IMAP) is easily supported, and if you want webmail, look at the SquirrelMail product.

ISA Server 2000 I have not used it. BUt it is webserver security. A lot of that can be administrated within apache, and firewall rules.

IIS -- If you are looking for straight webserving, in other words .html and .php, then apache will work for you. If you have strictly windows stuff -- the X controls and other windows only things, then you may have some trouble. This depends on your needs.

In order for us to help you develop your solution, I think we need to know more about your needs and desires. How many workstations? Backup solutions? Firewall plans? Do you want to build a Linux cluster? Any future plans for streaming?

I hope this helps you as a starting point.

Christian