About the New Geneva Study Bible...
If the New Geneva Study Bible sounds like it would be beneficial, and you're planning on ordering one...there are two newer and supposedly better ones out there. There's The Reformation Study Bible (NKJV) edited by Sproul, which was intended specifically as a revision of The New Geneva Study Bible, and as such would probably be better.
And now there's a newer one (June 2003)that I hear is even better: Spirit of the Reformation Study Bible (NIV). I don't have a copy yet, but from a reading of the reviews on Amazon, it seems like the best Reformed study Bible out there. In addition to the NIV instead of the NKJV, it has the Heidelberg Catechism, Westminster Confession, Westminster Shorter Catechism, Belgic Confession, Canons of Dort, and Westminster Larger Catechism. Also, Sproul is no longer the general editor, but Richard Pratt, professor at RTS in Orlando. Pratt also selected as the theological editors John Frame and J. I. Packer.
It'd be even better if a Reformed study Bible with the ESV was out there! But in any case, hope this helps!