iirc (and tbh, i'd rather not be corrected on this - could be pricy! :P ) that's not the way it works for education. That is correct for some of the MS Volume licensing schemes, but under the education licensing system you don't need to re-license a box that's already licensed with the same product.
i.e. A box with an OEM XP Pro license, you should be fine to run XP Pro on as is and in addition; IF you volume license other machines in your school you can also use the volume install media on your OEM licensed boxes (as in the doc I linked to a couple of posts ago).
Where the waters are muddied a bit (and what the software licensing houses don't always make very clear) is that the education Windows license prices are actually for upgrades only, so you would need another license (OEM or retail) in order to be able to 'upgrade' to XP under education pricing per box. So if you had machines with Win98 OEM stickers, or XP Home OEM stickers, you could buy education XP Pro licenses on the ~¬£32 pricing, use the volume media and as a bonus, use the volume media on your XP Pro OEM licensed boxes too. What you couldn't do is build your own machines, or buy machines with no OS license, buy the ~¬£32 education XP Pro license and run XP Pro. You need something to upgrade from (although Win95 does qualify - keep those old licenses )
That's always been my understanding anyhow. Plus, our old admin network which was a Hampshire CC managed jobbie were all OEM licensed but installed with volume media and no volume licenses were ever purchased. I always thought it rather odd that any VL scheme would require re-buying licenses you'd already paid for via the OEM anyway. :/
Around 80% of our machines have an XP-pro OEM sticker on them, so if the above is correct, then in theory I could save the school around 80% on its windows XP licensing.
The other issue here I've just thought of is Client Access Licenses for the servers. As I understand it, a CAL is included with the XP-pro license under a volume agreement, where as using the XP pro OEM license would mean you'd have to purchase seperate Client Access Licenses to allow these machines to use your servers.
Infact thinking through this, this may well be the reason we have all our machines covered by the volume license agreement. Going to make some phonecalls monday to clarify this me thinks.
You need to get seperate CALs for Server 2003, you don't get them bundled with XP Pro OEM or XP Pro Upg. they are a seperate item, cost around ¬£3 each.
If you run XP Pro on your machines and 80% of them have XP Pro OEM stickers on them then you only need to licence from microsoft 20% XP Pro Upgrades (assuming your other 20% have a COA from antoher version of Windows?) but you need 100% Server Cals from Microsoft. You may have them all under licnece as you can buy Software Assurance for new machines that have OEM windows on them.