I found this in a few different places around the 'net - hopefully it's helpful:

How to Change Column Settings in Windows Explorer

This article describes how to change the column settings in Windows Explorer. To change which columns are displayed, or change the width or order of the windows and folders in Windows Explorer:

• In Windows Explorer, click the folder, and then click Choose Details on the View menu.
• Click to select the check box of each item that you would like to add to the current view, or click to clear the check boxes of items that you do not want.
  
• To reorder your columns, click the item (but do not clear the check box), and then click Move Up or Move Down until the items are in the order that you want. Click OK.

Note: You must click Details on the View menu in order to display the details of the files in the selected folder.

To change the width of the columns, use the appropriate method:

Method One

• On the View menu, click Choose Details, and then click the name of the column that you want to adjust. In the Width of selected column (in pixels) box, enter the size that you want, and then click OK.

Method Two

• Widen columns manually by positioning the mouse pointer between two border buttons of the column headings, the pointer turns into a double arrowhead.
• Click and hold the left mouse button, and then drag the column to the desired width.