Question : Need to migrate off NT4 domain where in addition to NT4 server there are two 2003 servers and an SBS 2003 server on the network

I have four servers.  
EXCH1, running NT4, primary (sole) domain controller for the abc domain.
TS03, running Server 2003 Standard, member of the abc domain
2K03, Server 2003 Standard, member of the abc domain
SBS07, Small Business Server 2003, AD controller for the abc.local domain, with a different netbios name than "abc".

I want to end up with SBS07 as the "primary" AD DC for the network, with Exch1 retired, TS03 as a member of the AD, and maybe 2K03 as another AD DC (or a member if not).  This affects about 30 users and PC's...all the PCs are in the NT4 abc domain.  Exchange is running on SBS07 and there's user accounts there now in abc.local that are equivalent to the user accounts in the abc NT4 domain.  Obviously want to minimize time to accomplish this and user down-time.

Been so long since I've had to touch NT4 for anything serious, not even real sure where to start...and the NT4 box is starting to show signs of its advanced age.....

Answer : Need to migrate off NT4 domain where in addition to NT4 server there are two 2003 servers and an SBS 2003 server on the network

>>"From the company's perspective, their main benefit of SBS is inexpensive Exchange."
Unfortunately this is often the case. Not meaning to be rude, this site is littered with this philosophy and in most cases the company ends up spending more money in labor, than they would have with licenses for server std and Exchange. SBS is not Server std, and the known tools do not work with it.

You could migrate the users using ADMT, and I appreciate why you would want to, but there are a lot of differences with SBS including the basic AD structure. In many cases the problems do not appear obvious until a year later when you try to use one of the SBS services or add a service pack. The people that have the most problems with SBS are usually those that are most qualified with server std that refuse to use the wizards. Every SBS "guru" here had to rebuild their first SBS within a year because we tried to use conventional tools we were familiar with from other server versions. 3 rules with SBS, 1) install all services (even if you don't plan to use them), 2) use the wizards, 3) use defaults whenever possible.
This forum is more dedicated to supporting the SBS product and seeing it done correctly than finding workarounds just to get parts of it to work, so we are not a lot of help I am afraid.