Is Faith a work?

Just to give some background.  I am currently going through the book of John in my personal Bible study.  I have RC Sproul's commentary, and I recently started using Calvin's commentary (which you can find for free online at http://www.ccel.org/ccel/calvin?show=worksBy).  I love the way RC has laid his commentary out.  Each section of verses is covered in one short chapter.  This gives me plenty of time to read the whole chapter, then read the Bible verses again, and then take my own notes.  Calvin goes into more depth, which is wonderful and greatly needed in some sections of John. 
I am currently in Romans 6 in the area of verses 25-34.  Whend I came accross Calvin's commentary on verse 29, it struck a chord with me.  I understand that we are not justified by our works or anything in us, but how does faith fit into all of this?  I do understand that faith is a gift of God, Ephesians 2:8, but it is something that we must do to be saved.  I know that I've probably heard this before many many times, but God used this commentary to open my mind a little more on the topic of faith this morning. 

That you believe in him whom he hath sent. What is the import of the word believe, we have explained under the Third Chapter. It ought always to be remembered that, in order to have a full perception of the power of faith, we must understand what Christ is, in whom we believe, and why he was given to us by the Father. It is idle sophistry, under the pretext of this passage, to maintain that we are justified by works, if faith justifies, because it is likewise called a work First, it is plain enough that Christ does not speak with strict accuracy, when he calls faith a work, just as Paul makes a comparison between the law of faith and the law of works, (Romans 3:27.) Secondly, when we affirm that men are not justified by works, we mean works by the merit of which men may obtain favor with God. Now faith brings nothing to God, but, on the contrary, places man before God as empty and poor, that he may be filled with Christ and with his grace. It is, therefore, if we may be allowed the expression, a passive work, to which no reward can be paid, and it bestows on man no other righteousness than that which he receives from Christ. - From John Calvin's commentary on John 6:29