Man that's rough. I went through 5 motherboard ship-n-swaps with my 12" G3 iBook before Apple finally caved and replaced it with a new 1.5GHz PowerBook (on which I am typing this comment). Of course that's a lot easier to put up with when the cost of all that was covered under Apple's repair program (since it was a manufacturing defect causing the dead-video problems).
I think the next 18 months or so are going to be rough in terms of buying Macs. As Apple switches more of its product lines over to Intel, removing PPC versions as they go, and software developers continue to work on getting universal binaries out, things are going to probably be a little chaotic. Personally, I'll probably try to grab a last-revision G5 tower (whether I can afford it at the time or not) to use as a PPC legacy machine. ...boy, it sure seems sad to think of a dual processor, dual core, 2.5GHz G5 tower as "legacy" hardware.