Well, that was fun.
Spent the last few days attempting to clean up my network and upgrade my VMware servers to the latest software version (7.0). Unfortunately, that meant the onboard NIC wasn't recognized in either of my Dell servers anymore. That meant none of my VMs had any connectivity to anything. Thankfully I had two of these USB adapters lying around that are recognized by VMware's "community" drivers. Once I got those installed, everything has connectivity again.
Probably won’t be upgrading those servers ever again without replacing the hardware.