Dr. David Murray, professor of Old Testament and practical theology at Puritan Theological Seminary in Grand Rapids, Michigan, addressed issues related to this question in a recent conference at Fraser Valley Bible Conference in British Columbia. You can access the media from the conference by clicking here.
I thoroughly enjoyed listening to all the sessions, and was especially moved as Murray clearly demonstrated that the Old Testament is a manual for Christian living. I found his treatment of Hebrews 11 and 12 to demonstrate this point beyond the shadow of a doubt. It is not a manual in a moralistic sense of do this, do this, do this - rather, we live a particular way because we are looking to Jesus in faith.
In addition to these lectures, I have been thoroughly enjoying Dr. Murray's blog, "Head Heart Hand" and his weekly 30 minute podcast with Tim Challies, Connected Kingdom. I have been refreshed with the Gospel and gained helpful insights through these resources, and commend them to you.
"Is the Old Testament Still Relevant Today?" In a word, YES, and I encourage you to check out Dr. Murray's lectures to see how it points to Christ, shows us how to live, and shows us how to read the New Testament.