Photoshop :: Displaying Multiple PSD Inside Editor?

I am creating a website template which usually consists of a HEADER, FOOTER, (perhaps a LEFT, RIGHT) and a CONTENT center region. What I am CURRENTLY been doing is the following:

Let's say I am working on a Decoder page called Decoder.psd and in order to create the website layout, I create 5 folders in the layers pallete which contain the contents of each region of the layout.

1. HEADER
2. FOOTER
3. LEFT
4. RIGHT
5. CONTENT

Now SURE I can ignore the header, footer... but it makes it MUCH EASIER to work with designing wise when I can see exactly what the finish product will look like in realtime in the same screen. Unfortuntely there is a DISADVANTAGE to this which hense the reason for this posting. If I decide I want to change something in the ie. Header and footer design, I would have to edit each of the psd files individually and basically copy/paste the HEADER and FOOTER layer pallete folders so each of my template pages are updated.

What I am wonder is if there is a way to have say a DECODER.PSD file which only had the contents of the decoder deisgn in the layers pallete, and then be able to SHOW other layer contents (or perhaps just the end result) of another psd file in the design workspace?

Similar to how a FRAME would work in html. You have each layout seperated into individual html files (in this case individual psd files for each part of the layout regions) and DISPLAY other html pages (in this case, other psd contents) in specific areas of the page (In this case the workspace).