Well, probably not too much demand for this, but I've still got a legacy domain to support until I can get everyone moved to the new AD.

I was able to find the info on this here:

http://www.ozzu.com/mswindows-forum/getting-vista-join-nt4-domain-t76122.html

To add Vista to the domain:

1. SRVMGR.EXE on the PDC and add the computer name of the Vista PC.

2. On Vista PC run, secpol.msc then Under Local Policies > Security Options, Change the following two settings

- Domain Member: Digitally Encrypt sign secure channel data (always) - change to disabled
- Network Security: LAN Manager authentication level - change to "Send LM and NTLM - use NTLMv2 session security if negoitated"

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I was able to successfully test this in VPC.  NT4 on a 3GHz Quadcore is crazy fast.  I had an NT4 PDC with SP6 and VMA in under an hour.