Layout tabs in PostalCAD 2009 are much more versatile then previous versions. You can now left-click and hold on any layout tab and move it to a new position and you can hover your mouse, without clicking, over a layout tab to preview the contents.

Here's a quick overview of these two tips.

Left-click and hold on the layout tab you want to reorder.
Move the selection until you see a grey arrow to the left of the tab where you want to place it.
Your tabs are now reordered with the new location.
Here's the other quick tip on Layout tabs, hover your mouse over any non-active tab and a preview image will popup.