SixtyFourSwitcher is a preference pane that makes it easy for users to
switch between booting using the 32-bit version of the Mac OS X kernel
and the corresponding 64-bit version. The 64-bit kernel is internally
faster than the 32-bit kernel due to its improved caching &
improvements in the ABI, but the 32-bit kernel has better kernel
extension compatibility than the 64-bit kernel.

Compatibility
Architecture: x86 (Intel:Mac)

SixtyFourSwitcher requires Mac OS X 10.6 or later, as well as a 64-bit
CPU, such as the Intel Xeon or Core 2 Duo.

Mountain Lion users: This preference pane is obsolete in Mountain Lion
and later, since Apple removed the 32-bit kernel from the OS.