I dont know whether this is a feasible option for you, or is even a solution for your situation, but what we do, is purcahse 1 Volume Licensed XP key from MS, and build an image using the Volume Licensed media. This way we can distribute one image to all computers and dont have trouble with license keys. I was told by numerous top tier vendors, that as long as the workstaions have an OEM license on them, you are still within your license terms, even if you used VLK to install the OS.