I'm running EyeTV, iTunes, several web browsers etc. simultaneously, and sometimes there are jobs running in the background consuming all free cpu cycles. (For example, video format conversion.) The children have been playing games, drawing, experimenting a lot on this system.

The iMac has been stable without problems for a couple of months now. I'm not rushing into Leopard (Mac OS X 10.5) yet. I'm still waiting for version 10.5.2, and perhaps even version 10.5.3, until the upgrade. However, some new software requires (or recommends) using Leopard, so the time to switch is near.