I've been following OSX since beta and I haven't seen this tip anywhere. If you edit the com.apple.finder.plist file in /Users/username/Library/Preferences, you can disable the preview pane in column view.
NOTE: All angle brackets are shown as square brackets in the following examples -- do not change them from angle brackets!
Open the file in TexEdit or some other text editor and scroll to the following area:
[key]StandardViewOptions[/key]Within that [clmv] section, look for:
[dict]
[key]clmv[/key]
[key]ShowPreview[/key]Change the "true" to "false" (leave the "/"!) and then relaunch (via force-quit) the Finder. Now when you open column view, you will no longer get the preview pane! I found this out simply by looking at the preferences in the terminal using the "defaults" command and testing different values.
[true/]
Insert the following just below the opening '[dict]' tag under 'StandardViewOptions':
[key]clmv[/key]As in the above, make sure you use angle brackets, not the square brackets shown here. If you make a mistake and save a badly damaged file, just throw it away - the Finder will make a new one for you.
[dict]
[key]ColumnShowFolderArrow[/key]
[true/]
[key]ColumnShowIcons[/key]
[true/]
[key]ColumnWidth[/key]
[integer]186[/integer]
[key]ShowPreview[/key]
[true/]
[/dict]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20011004134523236