Everything with the migration went fine ... I pulled all 14 GB of data off the old box and dropped it on the new machine in a little over three hours (and got dinner out of the deal!).
With the file migration done, I got everyone's drive mappings cleaned up, shut the old box down, disconnected it and lugged it home. This was the first time in over 240 days that the system had been powered off. When I brought it back up once I got home, the NIC promptly died. And I mean died -- filled the screen with PCI bus errors, rolled over on its back, and showed Xs for eyes died.
Thank you, oh god of small favors, for keeping Murphy from doing me up the ass on this gig.
* "Old" in this case is a 1995-vintage HP Vectra tower with a 133 MHz Pentium with 96 MB RAM and a single 18 GB hard drive. The "new" box is a Compaq PC with a 450 MHz Pentium II, 512 MB RAM and a 4x18 GB RAID 5 array (51 GB usable space). Y'all say lebensraum now, y'hear!