With widescreen display becoming the norm in US and other cultural societies, and hours of tape that have been acquired in 4:3 modes, editors/producers are faced with a few new choices as to how to make their existing SD footage fit in the world of HD. There are several courses of action that may be taken, but each carries with it a small cost. However, as we move towards the future as editors, we must consider the fact that "Uncle Joe" bought a widescreen display (whether its HD or not) and he doesn't want to see pillarboxes on his screen, nor does he want to see a wedding video in which his 5'7" neice has become a 5'1" oompa-loompa either. Of course, if his display is a high def display, there is a great chance the television will autostretch the image on it's own and may get the aspect ratio correct, but lose a tremendous amount of resolution in the process. In the near future, media formats will be exclusively widescreen; 4:3 is all but dead, and you'll need to learn to use widescreen as a shooting and editing format, and better sooner than later.
So, how do we avoid softening our image, filling the screen, and ensure that our images look as great as we've intended?

First and foremost, start shooting 16:9 NOW. Get used to it. SD or HD, start shooting. early to become familiar with the additional implications of shooting a full third more area.

Second, in post you can immediately begin dealing with the 4:3/standard aspect ratio display right now.

Here are a few methods, with my preferred method at the end of this brief tutorial.

We can use the Pan/Crop Tool in Sony Vegas/Vegas Movie Studio to make our image fit the full frame, and this is a fairly easy and painless technique. In fact, there are scripts for the full version of Vegas from John Rofrano and VASST that accomplish this for you. The downside to this technique is that the image loses resolution due to being cropped and effectively zoomed. While for many images this may prove to be no big deal, it could present problems for images with very fine detail in small horizontal or vertical lines.

To use the pan crop tool to bring the 4:3 image to widescreen, start a new or existing project with a project property set to DV-Widescreen (either NTSC or PAL)

All images will require processing of some kind if this is your chosen method.

Filled Frame
This is another technique that works, but again affects the resolution of the image, much the same way as Pan/Crop does. With the same project open and same media on the timeline, open the Track Motion tool and size the image to fit the entire frame. This may involve some slight stretching as you can see in the image below but again, it's a viable tool and may work for your particular needs. The image is stretched long and squished vertically in this preview, but no resolution is lost.
My favorite method however, leaves the original image at original resolution, but is sized to fit in a widescreen display with no loss of original quality.

Filled Pillar Boxes
Open the new or existing project as a DV/PAL widescreen project. You'll note pillarboxing on the right/left sides of the media. This is the area we're going to exploit. Media can be placed behind the original 4:3 frame that is either contrasted to the original, or complimentary to the original image. We'll start by adding a new video track beneath the original track.

Copy the original media to the new track below.

In the lower track, Use the Pan/Crop tool to bring the lower image only, to the widescreen aspect ratio. Right click the image in the Pan/Crop dialog and choose "Match Aspect Ratio." Now add Gaussian Blur to the lower image only.. This will blur the background of the lower copy of the image, providing a matching background to the original. Extreme Blur usually works well.

Now you have a preview with matching colors and motion, that won't distract from the original image in most cases. On the other hand, you may wish more contrast. Adding Sepia, old film looks, color curves, etc are a few options that can be used to cause the background and the foreground to mix.

If the media doesn't present well by using a reproduction of itself with FX, consider using generated media in the background instead. Vegas is filled with generated media that may be used for backgrounds.

You might find the noise easy to work with as well.

Finally, there are all sorts of background libraries from developers like Artbeats, Sony Visions/Textures libraries, Digital Juice, etc that may be used beneath the 4:3 video.

Use the backgrounds in your library for interesting and creative looks. Just be sure that the background media doesn't distract from the original media.

There are a couple of other options available, the above method is my preferred method in most instances. However, when bringing the SD into an HD project, it may be too obvious that the SD is being scaled to the HD resolution. The afore-mentioned techniques help reduce this issue, but not completely. So, it might be in your best interests to consider laying SD into an HD project with frames or resized footage that allows the HD to look great, but allows the SD to look great as well.

In the images above, I've added the Borders filter to give the images the appearance of being photographs, but containing video instead of stills.

These are all very simple methods, but may not be immediately obvious to editors that need to keep original resolution and image quality as high as possible in their programming. Using Track Motion and Pan/Crop, many things become very easy in image aspect and size manipulation. Practice a bit in the spare moments, you'll quickly come up with a format that works best for you.