Small Engines (Lawn Mowers, etc.): RX75 Engine, john deere rx75, google

Question
I have a John Deere RX75 which just started smoking like crazy and blowing oil.  It runs a few minutes and then dies.  So it's my assumption that the rings are gone.  First, is this a good assumption...I still need to check compression.  

Next - is it even worth fixing?  Would it be a reasonable job to dig into myself and get the kids involved in small engine repair?

Thanks,
Tim

Answer
first hand what are we working on could you give me a model type and code on it so I no what it is and yes there could be a ring problem and anybody can rebuild a engine very easy but mainly you got to get a book or do a google on it to the the specs so everything is set up right a rebuild kit for an engine would run you around 120. to 130. I take it this is a old engine so if it is blowing oil past the rings you will have to open it and change them get me the info and I will do some homework on it thanks