Actually, that *was* the issue. The funny thing was, I did inject the drivers into the boot images via WDS and via DISM. I used the DVD that came with the board. It took the drivers without a problem. However, it was only after I went into the WinPE environment (Shift-F10) after the error, and tried to load the drivers using drvload driver.inf that for some reason, the image refused to take the 32-bit driver. So I got the newest driver straight from the RealTek site and injected those -- it took. Everything worked from there...
Basically, from command prompt, ipconfig yielded no IP address. Downloaded the driver, did drvload driver.inf, then ran netcfg -winpe. That worked.
Is there a way to restart the setup sequence from there?