prepaid SIM card im Madrid (airport or city?)

Hi again,

I am planning not taking my Blackberry as I don't want to carry my work with me :lol: But instead I am going to bring my old small phone, to buy Spanish SIM card and to sms the number to those few people whom I would like to stay in touch. So the question is WHERE to buy the SIM and WHICH one?

Ideally if there is a possibility to buy something in Madrid Airport. I will fly with Lufthansa, so that should be T1. Anything there? Up to now I have only been transferring in T4 and, be honest, have never paid attention to mobile providers shops if any. Anything on the subway station? Another possibility, I guess, would be to look something on my way out of Madrid. I guess I will just keep an eye on sings telling: Yoigo, Movistar, Vodafone, Orange, Simyo... Any places to take a look to (like grocery store, newspaper kiosks)? And then the question is what to ask when I see them? How "prepaid SIM" sounds in Spanish? :roll:

My Spanish colleague said that you have to register the SIM since a few years. I have an experience in Germany and in Russia that one has to have local address in order to register new SIM. How does it work in Spain? Should I bring anything which confirms my address (it is not mentioned on my German driver license or in my Russian passport)?

Finally, any particular recommendations on which SIM to prefer? I will need to make calls inside Spain (for reservations if needed), to Germany and Belarus (to let my family know that I am still alive). 8)

Any advises, recommendations and references are welcome
Natalia.

To answer my own question

I have bought a SIM card in Tres Cantos, in the huge supermarket named Carrefour. There was a department with "brand" SIMs like Vodafone and also there was prepaid SIMs from Carrefour itself. Filling papers, showing passport, dropping some extra money on the account took ca 10 minutes and it started working within half an hour after. I bought SIM from Carrefour (there was a selection on stands at each counter, had to look for prepaid package) though I am not completely sure which one would be better of price, actually. Carrefours gave better deal for internal Spain phone calls and incoming calls were free, but calling abroad was quite expensive. Vodafone was giving better price for international calls but more expensive local calls. And it looks that in total my roaming would be not much more expensive then phone calls with the local SIM cards.