Post Effects - preview

Hi

I am working on a project which uses a lot of post effects (highlights and glow mainly).

So far as I can tell the only way to preview what you have done is by rendering to picture viewer. I need to use an alpha channel for compositing later on.

My problem is that in the Picture Viewer, as my image renders I can see the alpha channel, kind of overlaid onto my image. This is really ugly and stops me from seeing how my post effects look.

I've tried the options in view, channel etc (in picture viewer) but I can't change it so it looks normal. I am having to load the image into my compositing software just to preview 'on black'.

Am I missing something?

ta
John