Present perfect simple vs Present simple continuous

Remember that the Present Perfect Simple is a tense that refers to the PRESENT NOT TO THE PAST. It is used to describe an action that started in the past but that has an influence over the present

- We usually use the Present Perfect Simple to talk about a state that started in the past and continues in the present. We usually use the PPS to say how many things are finished.
                             They've been  married since 1972.
                             They've publised 390 books since the company began

- We usually use the Present Perfect Continuous to talk about an activity that started in the past and continues in the present (we focus in the process). We usually use the PPC to say how long an activity has been happening.
                            They have been publishing guidebooks for 30 years.


Here you have some links if you need more information:
http://www.aulafacil.com/Ingejerc/Lecciones/Lecc21.htm
http://www.juntadeandalucia.es/averroes/~14700596/departamentos/present_perf.htm

Now... It's time to practise!!

http://www.autoenglish.org/gr.percon.i.htm
http://www.englishpage.com/verbpage/verbs7.htm
http://a4esl.org/q/f/z/zz28bka.htm