The new iMac will be the wife's. Her current one only managed about fourteen years with one set of hardware (rubbish really). I had to rebuild it on a donated G4 about a year ago when the power supply died on the old one, but now it's time for Intel really.
We had problems with the eMac series (bought two, both motherboards failed), but with that exception, they have been highly cost effective compared to Windows machines. Very low maintenance, both hardware and software, and simple networking. Contrary to popular mythology, format compatibility hasn't been a problem either. At one point we had four in the house simultaneously (one original iMac, two eMacs and a G3 tower) - my PCs were a bit lonely! Now we're down to three: iPad, Macbook Air & ageing G4. I'm not keen on the closed architecture of the iPad, but it is safe, and I have little to do to keep it going. It's WiFi is relatively weak though - my Samsung tablet works happily where the iPad won't.