Thanks for the response. I've been trying to keep the transparency but no matter what I do the size seems to end up at around 600Kb.

I have checked it in XaraX Pro and the pixel size is 820 wide which is what it is meant to be, and exporting it as a gif or png shows it as being reduced to around 168Kb, but when I then import it into WD6 it ends up as just 500pix wide and scaling it back to the 820pix wide the file seems to end up at around 450-600Kb. I have just tried making an 820pix wide bar in Xara and importing this to WD6 and it imports as a 500pix wide bar. Any thoughts on this?