4990 Drivers for Snow Leopard

[Ken Lee]

If you reboot, the 64-bit setting goes away. Here's how to enable it permanently, according to http://blogs.zdnet.com/Apple/?p=4716

Edit file /Library/Preferences/SystemConfiguration/com.apple.Boot.plist

Change this:

<key>Kernel Flags</key>
<string></string>

To this:

<key>Kernel Flags</key>
<string>arch=x86_64</string>

... and save the file.