Running Novells networks, and the PC is often better as both a client and a server - but I write this off as Novells inability to write good code. So if your only purpose of a computer is serving network stuff, then Unix is the way to go. So there are many little gotcha's in system performance behavior - and there are many tradeoffs in system designs. In most cases - I usually like the Macs choice of tradeoffs. Those will be your real world results.
Percieved performance is which machine feels faster.
Yet in user interface design you learn that users are sometimes the worst gauges for performance. If you want to understand the realities of perceived performance then see Perceived Performance . The Mac is faster in areas where it counts. There are certainly small areas where the PC's beat the Macs - but those narrow focus is only useful if those are the only functions you are going to do. Gaining a few percent on a file copy is not as important to me as being secure in the knowledge that what was written to the floppy is really there.