Anyone successfully imported users + SIDS from NT4?

Here's the deal. My company is seriously considering a migration to G5 Xservers running OS X. However, because of other mitigating circumstances, we will be forced to remain with MS Exchange for e-mail. What I need to try to accomplish is: Migrate all users, servers + SIDS (so they can still access exchange) from an NT4 domain (NO Active Directory) to Open Directory + Samba on OS X. As an alt, I have available to me, a method that would allow me to upgrade the domain to AD if that would make the transisition any easier. I've been scratching my head for quite some time on this (I have an XServe and an NT domain built up in my lab) and have yet to be successful in this task. (and yes, I've read all the articles here + the howtos on samba.org repeatedly ad nauseum). OS 10.3.4's flavor of Samba has a bug that will not allow net rpc vampire to work. So, that isn't a viable option. I've read the Apple whitepaper "Mac OS X Server Windows Services Administration for version 10.3 and later", dated 2003, and the whitepaper is incorrect in several places. i.e., there is no native MS tool to export users in a tab or comma-delimited file from an NT4 or AD server. I'd really like to go with XServes instead of Win 2k3, so if you've got a way to do it, now's the time to tell me.