See http://www.robgalbraith.com/diginews/2003-01/2003_ 01_07_macpc.html. The author is a Mac guy and a professional photographer. Did some of his own benchmarks because he didn't believe the Apple "party line" that the Mac was faster than the PC. Be sure to read the "Author's followup" since he took a lot of bashing from Mac addicts. I mention this specifically because of how many people think "everything just works" on the Mac. The author says (emphasis mine):

For a major project that ran through much of last year, I got up close and personal with Windows XP Professional running on the humble Dell box in the speed report. I connected a whole raft of pro digital SLR cameras, over a dozen card readers, plus several CD writers, several inkjet printers, a flatbed scanner and a film scanner.

Every device connected and worked without a hitch, many of them sucking their own drivers from the ether and configuring themselves. Way, way cool.

On the Mac, it was as it always has been for me dealing with pro digital photography peripherals, whether in OS X or earlier iterations of the operating system. Some devices worked fine, though many required the manual installation of drivers, while some devices, and especially USB and FireWire card readers didn't work at all.

The original article compares six different RAW processing applications, crunching files from 8 different digital SLR cameras, have been put through their paces on 4 different computers: two Macs running OS X 10.2.3, and two PC's running Windows XP Professional.

Conclusion

What's there to say but the obvious: The fastest dual processor Mac has been soundly thumped by one of the fastest single processor PCs. If this report had included a dual processor PC, the PC's margin of victory could have been even greater (at least in the multitasking tests, and for other PC software that may be optimized for multiple processors). Even the Dell, a modestly equipped desktop by current standards, matches or bests the dual 1.25GHz desktop Mac in numerous benchmarks."