The install media is independent of the licensing. You can get Windows XP install media w/SP3 included and just use any license keys you already have. You can also create your own XP install media to include SP3, and whatever other patches you want--search for keyword "XP slipstream".
Why do they need new licenses if they already have existing licenses? If you actually need more, you can get more license keys from anyone that can sell XP. Try ebay, or maybe a hardware leasing company. Also, if you buy old recycled PCs they usually include a license key. You might work out a deal to buy license keys from equipment that's going to disposal. /* PLUG: http://plug.org, #utah on irc.freenode.net Unsubscribe: http://plug.org/mailman/options/plug Don't fear the penguin. */
