The author's problems start with an un-condomed IE, and probably through surfing a few porn/warez sites. Everyone knows that the first thing you do with a virgin Windows installation is go to either mozilla.org or opera.com and download either browser. :-)
That said, Windows XP x64 is pretty decent if you have modern hardware. 64-bit drivers are a hit-and-miss experience with older hardware, but that's to be expected. It is based off Server 2003 SP1 code, so it's actually a much newer release under the hood than regular 32-bit XP, as well as being a lot more stable and snappier. Pentium 4s don't actually do real 64-bit, so it's pretty useless running a 64-bit OS on a P4 with EMT64 extensions, but if you have an Athlon 64, then the benefits are visible right away.
As for OS X and 64-bit ... last time I checked, only a few core libraries are compiled for 64-bit, allowing some reduced 64-bit functionality (like 64-bit memory addressability). Hell, even the kernel is still 32-bit. XP x64, on the other hand, is fully 64-bit through-and-through.
That said, I still prefer using OS X on a day-to-day basis.
