MS won't sell any W2k key any more.
Buy it from eBay.de, eBay.fr... for some 8€ a key, maybe 20€ with an original disk. They look more expensive at eBay.com and eBay.co.uk.
Box versions Cd don't accept Oem keys. Language is unimportant from my trials. Take a full version, not an Nt4 update.
O yes: in every EU country where the case was raised, Justice told Oem licences could be resold and reused on another hardware. But check it in your country.