Nick,
The technology exists for the most part. It is more an issue of putting the technology together into a design. The Ares rocket will be the mode of delivery to destinations like Mars. If it runs on schedule (these things seldom do) it will launch humans into space for the first time in 2014. It will be powered by Pratt and Whitney Rocketdyne J-2X engines. The spacecraft the humans will physically fly in will be the Orion Capsule. It will have its first manned flight with the Ares rocket in 2014. A possible lunar landing is projected for 2019 and a first Mars visit has been hinted at for 2037. If funding was unlimited and schedule was a priority how fast could be get to Mars? Well a totally uneducated guess is before 2025. But we are just going to have to wait. I personally don't think sending humans to Mars is going to do much for science or the human race. Many projects would be of more scientific merit. It's like the ISS... sure its cool there are humans in space 24/7/365 but it is the equivalent of a high school science project in my book next to what others programs do for science and at 1/100th the price.
