Considering the Insane: time to get started?

So I have been thinking and looking and contemplating things lately. I really like Triathlon, and want to do a HIM and eventually an IM someday. but there is a lot standing in my way, things like needing a decent bike (something other than my trek hybrid - which is fine for sprint and even olys but not longer distances) Also due to a recent injury which kept me from running, I realized that over the last year I have really come to enjoy just getting outside and running. Given all of this I started to look into long term motivational goals to focus on other than Ironmans.

In looking what I found was what could be a decent step system to ultra running through strictly local races. I just want to throw this out and see what people think of the timeline or if it could use some adjustment.

there is a Half Marathon around August 6th, 2011. follow that up with the Seattle Marathon in November. Then I would have a long winter and spring of running and slowly increasing Mileage. The first weekend of June 2012 there is a 50 miler (Rainier to Ruston) and hopefully follow that up with the cascade crest 100 at the end of August.

The farthest I have run before was a half Marathon last year and I am currently starting to build my miles up again as I slowly recover from an injury. So does this plan sound solid if I can dedicate myself to the training and put in the time? Or would it be wiser to put off the cascade crest for a further year out, till 2013?

Thoughts, comments, ideas, encouragements, all accepted.