Present simple or continuous?

Differences between simple and continuous present, explained in Spanish, with exercises:

http://www.vitutor.com/gramatica_inglesa/verb_tense/present_simple_continuous.html

Summary of both tenses, in Spanish:

http://www.english-area.com/paginas/psimplevspcontinuo.pdf

Explanation and exercise, in Spanish:

http://www.aulafacil.com/Ingejerc/Lecciones/Lecc17.htm

Explanation of both tenses and exercises:

http://teachermarta.blogspot.com.es/2008/04/repasa-presente-simple-y-presente.html

Quiz about both tenses:

http://esl.about.com/library/Spanish/bl_spbgpresorcont.htm

Explanation in Spanish with the possibility of listening to the examples:

http://www.ingles-practico.com/basico/tiempos-verbales/presente-simple-continuo.html