My Curve has v4.2.2.89 (Platform 2.4.0.39)
My question do you think it is even worth it to Download v4.2.2.166 (Platform 2.4.0.73)? Another question, how exactly do you resend the Service Books? and why exactly would you need to?
If you are not having any issues with your phone, then I would not worry about updating it. I enjoy updating my phone as it is fun. When there is a need for it, typically you will get a message from your service provider prompting you to do it. Alot of us here on cb.com like to be ahead of the curve (pun intended) on the lastest and greatest software, gadgets, etc.
Also, if you are using ATT, the latest software they are using is .170, not .166.