Advice needed on light placement

Hi all. Again I need some help and I know this is the place to get it. I am trying to get these nice baby shots with completly white background. I am using muslin and it is working pretty ok. But I have a problem that I have to make the lights to bright to white out the background.
How far should I have the subject (i love calling her a subject) from the background? And where should I place the lights? Any sites or suggestion for setting up these shots would be appreciated.

Thanks!

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I light my white background by firing three flash units off where the ceiling meets the wall which allows the light to wash down the wall and out across the white floor to about 6 feet. I place my subject at the 6 foot mark and then allow my main and fill lights to complete the lighting of both the subject and the foreground. In your image there is ghosting around her arms because the background light is too powerful and she is too close to it. To keep a white background white it must be between 1/2 to one stop MORE than the combined main and fill when metered at the subject. Ghosting will appear if you exceed this level of illumination. It appears yours may be more than 1/2 to 1 stop. I've posted an image below showing my technique.

Benji

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Thanks for the reply. I am going to try what you suggest. I only have 2 lights and that may be my problem. But I will also try to bring the subject further away from the background and see how that works.
More suggestions please. Thanks again.

If you put one of your lights on the background it will possibly take care of it, but with only one light on the subject, your going to have awfully flat lighting. Try a reflector on the opposite side of the main light to bounce some of the 'wasted' light back into the shadows. If that doesn't work you may have to get another light.

Benji