I have a question regarding switching to a Mac. In an ideal and cost-free world I would be buying a new Powerbook. However, I was thinking that I could "get to know" a Mac by trying out an old G4. My primary desire for the computer is to install the new operating system and be able to use some of the more recent software. I would like to learn the system and the programs. As I am a PC user I am having difficulty understanding the processor speed. That is, how does the the processor speed translate to a PC processor speed? I understand it is like comparing apples and oranges, but I want to get a rough idea of whether or not I am making a sound purchase. Also, to what extent can I upgrade the computer? I understand I can put in RAM and different drives...but I can I put in a superdrive? Can I get a processor of a higher speed? The G4s I am looking at are not the ones on apple.com now. They are the ones that came out last year or before. For argument's sake, if I get one of the "slowest" speed processors, will I still be able to do what I want to with the computer? Will I be able to fully appreciate newer/the newest Mac software, Jaguar, etc.? Will it be noticebly slow compared to a 2.0 Pentium 4 computer? Thanks.