ok im trying to get a good workflow in cs5 which i thought i had but now when i try to nest the hd sequence to the sd sequence and then downscale "scale to frame size" the scale ratio seems incorrect i have bars either side on the preview screen maybe ive missed something?

Im trying to downsize hdv1440x1080 50i 16:9 to sd 720x576 pal 16:9

The bars in the SD frame are normal. They should be 8 pixels wide on each side. The reason for this is that the SD frame is not really 16:9 (or 4:3). It´s a little wider than true 16:9. The HD frame is really 16:9. In the past, many NLEs fudged the difference to avoid the bars when downscaling, but this results in a slightly stretched image, as you can imagine. Now Adobe and others are using the correct math, and thus the bars. You are placing a 16:9 HD rectangle into a slightly-wider-than-16:9 SD rectangle.

If you don´t like the bars, I should say pillars, you can change the downscale percentage so that it fully fills the SD frame. You will now lose a little image at the top and bottom, but it is an alternative.

Now if the pillars are wider than this, or the image is distorted, there is a problem with the settings.