Snow Leopard Client defaults to 32-Bit Kernel

Mac OSX 10.6 includes 64-bit versions of various applications, the default kernel setting is to boot into 32-bit mode. To boot the 64-bit kernel users have to hold down the "6" and "4" key at boot time. (Holding "3" and "2" will cause 10.6 to boot back in 32-bit mode.)  For OSX 10.6 Server the kernel boots into 64-bit mode by default. To make the change permanent users need to edit com.apple.Boot.plist and change the configuration. There is also a issue with older MacBooks only recognizing 3GB of ram out of 4GB if they are equipped with the 32-bit EFI chip. Apple claims many of the features are not completely ready yet, as they do become available they will be incorporated into updates. Their goal to to provide a stable transition to a truly 64-bit platform. The Finder, Mail, Safari, TextEdit, Preview are all 64-bit along with Mac OSX server. 

To check your EFI enter the following command in the Terminal

ioreg -l -p IODeviceTree | grep firmware-abi

The result should be the following. 

| |   "firmware-abi" = <"EFI64">

Now you can edit the com.apple.Boot.plist changing the key value for Kernel Flags.

// default 32-bit mode

<key>Kernel Flags</key>

<string></string>

Change that to:

//64-bit mode

<key>kernel Flags</key>

<string>arch=x86_64</string>