Issue resolved --
In my particular case, I was using a non-default data store. For standard installations (no third-party drivers), I had no problems whatsoever. However, when I tried to do a third-party driver installation, it failed due to the missing utilities (i.e. xcopy) in the root level of my data store.
If you use a non-standard datastore (not the installed /pxestore), make sure you copy all of the files from /pxestore to your new datastore