Predicting elections two years ahead of time is a fool's errand (no offense intended). In an arena when a week can be an eternity, there are way too many unpredictable things that could happen in two years. I would be very surprised if 13 Senate seats switched parties in 2006. I could see either party picking up a couple of seats but barring some HUGE event, I doubt either party goes +5.
I don't see my former Congressman Nethercutt beating Cantwell. She is a weak candidate but unfortunately I don't think that George is a strong enough candidate to overcome the disadvantages that Republicans face in a statewide race in Washington. If Rossi loses the Governor's race, he is the man who would beat Cantwell in 2006.
NetherCutt came on very strong towards the end of the campaign, and he's now known statewide. He has a much better chance of winning in 2006.