A new operating system...the vista preinstall lasted an hour or so before she asked me to replace with Kubuntu, which it's had ever since)
A new hard drive (daughterling pushed it off the end of a coffee table)
Two new fans (I cleaned up the cpu and gpu and applied arctic silver before reseating the fan and heatsink)
3rd keyboard (said daughterling pulled off a number of the keys, 2nd got coffee spilled over it)
The screen will need to be replaced since there's a bunch of dead pixels in the middle of the screen, and the mouse buttons could do with being replaced since one of them is soft and doesn't click anymore
Other than that, it's running well.