Though I believe Pumarosa is the best bilingual Spanish/English site to use for Spanish-speakers to learn English, there are quite a few others. I’ve recently put several new links in the Spanish section of my Bilingual Exercises page (by the way, Pumarosa is the first link listed there).
These new links include Vocabulix and a site called Learn English (created by the same person who has another great site called Learning Vocabulary Can Be Fun, which can be found in the Vocabulary section of my English for Beginners page).
Learning English through a direct translation system can be problematic and, over the long term, potentially detrimental to the language learner if that is the main method of teaching and learning. In fact, even without my saying anything, my students quickly figure that out for themselves. However, now and then they like to visit these bilingual sites and it’s fine with me when they do.