If you´re in Puerta del Sol it is definitely worth checking out FNAC in Callao before buying at El Corte Ingles . FNAC is French owned , I believe , and is a huge store for DVDs , CDs , computer games , books etc... . Also , if you want to find 2nd hand cds go to Calle Montera where there are a couple of small but , if you´re interested in music , fascinating stores !