The G-4 is an Apple tower that was introduced when they went to the first version of OSX. I own a G-4 with Dual 833 processors. It is faster than a Pentium 1.8 G.
And for all those who poo poo MAcs a man in the software industry dropped this fact on me: 95% of most entertainment media ( games, music/TV production, professional photo/printing) is created using Macs ( or SGI if it's EArts games). Of course, their market is pretty narrow which is why 95% of the world owns/works with PC's.