This is similar to a question I just answered concerning Intel vs AMD chips, and the same applies here. Megahertz are not the be-all and end-all of processor benchmarks. I have not tried one myself, but I've heard the new G5 is a rocket. I'm not a big fan of MacOS,(plus I like to build my own) otherwise it would be quite tempting.

I use both Mac & PC (windows) though I prefer the Mac for day to day use. In terms of speed, the top end Mac (g5) is about the same as the top end PC. Both machines have their specialty areas where they outperform the other. The people I know who have Macs or PCs that are relatively new don't complain much about speed. I wouldn't worry about it and focus on the software and the overall user experience.

This is going to get a lot more interesting in future when you will increasingly see slower processors being able to do much more work than faster processors. Basically performance is not just dependant on how fast (MHz) your CPU goes at but also how efficiently the transistors on it are used. Technology like Instruction Level Parallelism has been used in the past to improve performance (predicting what commands are going to be run). AMD CPUs historically give greater performance for less MHz than Intel for example. Moores law states that the number of transistors on a piece of silicon will double every 18 to 24 months. Historically these transistors have resulted in doubling of speed every 18 to 24 months. However as MHz of the CPU have increased at this fast rate, memory speeds have not (doubling about every 6 years) and so a doubling of CPU MHz rarely results in anything like the increase in performance you would expect. Companies like AMD, IBM and in particular SUN are concentrating on throughput computing. Rather than using the extra transistors to double the MHz, they are creating multiple cores on a single die. The Mega hertz will remain the same but the amount of work will increase. Combining this with threading (another metohd of many tasks simukltaneously)- this will result in much greater increases in throughput (the amount of work done) than we have had in the past. With dual core - you can think of the computer doing two things at once rather than one thing very fast. AMD will be launching dual core CPUs this quarter, IBM and SUN have had them for a while (note IBM make the CPUs for the MAC so I assume this technology will benefit the MAC soon). Sun are developing CPUs with 8 cores each with 4 threads - so over 30x the current performance but still only one CPU. This is due out in 2006. One of the benefits of this increase in amount of work done (throughput) without increasing the MHz will be less power requirements for the CPUs and therefore less heat generated. Intel are also developing dual core CPUs but are behind the curve. The other factor of course is what O/S you run on the processor - Windows v's Linux v's Solaris v's MAC OS with some being restricted to only some types of processors, but thats another can of worms....