Again thanks!
I love doing intervals on the Concept 2 and found that interval work helped me increase my pace greatly. That said, in trying to get fast, I started getting lower back pain. I guess I was losing my form.
I have since slowed down and focused on pushing my heart rate up (and keeping good form). Also, I have added some lower back stretches which seem to have helped.
I also just bought an indoor trainer for my mountain bike (ordered a Kurt Kinetic Road Machine 2.0 from REI) to mix some indoor biking in with the rowing. I used to bike on a local trail, but traffic to the trail and at cross streets has gotten bad that I have given that up except on special occasions.