Exchange Server Dilema

A Quick Rant:

It is time to start planning for server upgrades at the company I work for. At the center of our network, we have an exchange 2000 server loaded with public folders. Public folders are crucial to our daily work and are used to organize all current publicity tours.

Unfortunately, Microsoft has planned to discontinue support of public folders after the Exchange 2007 release. From what I understand, they are available in the new release (2007), but not by default and will not be available in future releases. The system requirements also up the ante for an exchange upgrade, and our current hardware will need to be upgraded as well…which brings me to my dilemma.

I am leaning toward a recommendation for upgrading to Exchange 2007 and migrating to new server hardware required as well, …OR… do I consider the alternatives?

1) I have done some research on Exchange replacements and it seems that Scalix or Zimbra are as close as they come and they actually look pretty impressive. These run on linux based platforms and would run on existing hardware with public folder support. But this doesn’t come without it’s potential pitfalls.

The transition from Windows 2000 – Active Directory – Exchange combo to a Linux – LDAP – Scalix/Zimbra is not exactly an easy way out.

How does LDAP compare to AD for use with user/group authentication?
Can user and group accounts be transfered from AD to LDAP and maintain network permissions?
Can users be managed in the same way using LDAP as they are in AD?
Can I use Scalix/Zimbra with AD and forget the idea of needing LDAP? (after all, AD is pretty much just a modified LDAP).

2) Do I recommend the Exchange upgrade and try to find public folder replacement or develop a custom in-house replacement.

I like the idea of breaking the windows licensing trap and the potential savings, but at the same time, I am cautious about the support available with the alternatives, not to mention changes required make such a transition. I tend to think that the the second option is likely the easiest and more hassle-free of the two, however, I have yet to come across anything that works like public folders in a stand alone application.