I have also been having no luck establishing a PPTP connection to version 4.1.2 (running in server-only mode).
If you haven't seen it yet (maybe it's not applicable to your situation), there is a bug fix for PPTP-VPN on the e-smith.org site, for server-only installs. That didn't solve my problem (I believe that I have now implemented the fix correctly).
I confirmed that I have 128 bit enctyption on my NT 4 machine (SP6a). I have opened port 1723 and allowed PPTP and IPSec pass through on my Linksys router (latest firmware upgrade completed). A port scan shows 1723 is open.
I have also tried both user and admin accounts and neither works.
Sorry that I haven't offered any help, beyond the bug fix suggestion. I am also looking for a solution to the e-smith server not responding to PPTP.