Gods, I don't like technology some days. First, thanks for the suggestion, though that was one of the first intervals I tried tweaking to no avail.
However, in the time between my first post and now, something happened and the two machines have different IP Addresses. I still don't think the mechanism for recognizing computer renames worked properly (the old machine is missing data from my custom fields), but it at least updated the MAC address for some reason. I'm set Win32_NetworkAdapter back to 0 for the time being, but if there are any other suggestions, I'd appreciate it!