If you can trust the seller to be truthful, then yes, it looks like a good price for a nice bike with very good components. No mention of pedals; minor thing, but keep in mind.
You have the article from bikesport; I didn't read the whole thing, but does it say what the original retail for it was in 2003?
At $850, I would think it is a good deal. It is 5 years old. But still probably a good value considering the components and if everything is in good working order.
Doesn't seem too bad. If that picture in the ad is the actual bike (which I doubt -- looks like a copy and paste from the Cannondale website), then one of the first things you're going to want to do is re-run the derailleur cables. That's one apalling routing. I haven't seen cables run like that since the early 90's.