I got rid of my PPC equipment in preperation for moving. I had a PMG4 400MHz Sawtooth that I overclocked to 533MHz with a 133MHz FSB using a 450MHz CPU. I also had a 1.25GHz eMac and a 2005 2.0GHz DC PMG5 with 6GB of ram. I loved that G5.
Couldn't care less about the G4 equipment though, they were just play machines. The 1.5GHz PowerBook should be still plenty powerful for web surfing which is what notebooks are meant for these days, so if its cheap enough, then yeah its not a bad idea.
Stuff.