"Mine is a 2003, with 136K on the clock.....Not even a month after I had it, check engine light and IMA light came on."
Wow

That's pretty rare, especially with only 136k miles. If anyone wants to know just how reliable the HCH is, go to Consumer Rerports. They recently featured the reliability of all the different cars and how they stacked up. The Honda Civic Hybrid was MUCH more reliable than all the others. The Prius and other hybrids also got signifigantly better scores than the rest.
THe reason I think hydrids are this reliable is because 1) Japanese car companies make them and 2) I think they are over-engineered because they don't want reliability issues to tain their hybrid nameplate.
From what I have read from forums and the like, it seems to me that a HCH II (SECOND gen.) would have the battery back replaced once over a lifetime of 300k miles over 10 years.
However, If you drive a HCH like a sports car in the mountains in the freezing cold, of coruse, you can expect the battery to die much sooner than that. But, under any normal conditions, I'd think that the battery back would last for a looong time. (Warning: this is just my opinion as an enthusiast. I do not own a HCH [yet])