Creating a Smooth Gradient without Banding?

Hi there:
I shot a TV set and we decided to add a white to transparent gradient on the otherwise black TV screen to create depth for shaping.
What I did was create a circular gradient in the top left corner of the TV set. It has been set to go from White to Transparent. Then I reduced the opacity to around 40% to make it seem more realistic. The problem is that there are very visible bands from where it starts to where it fades out. These are visible from 100% opacity and downwards. I want the transitions to be smooth smooth smooth My Layer Blend mode is set to normal Will changing the blend mode help? I did try to use different blend modes and nothing changed.
Please help
Thanks

W
N.B: I'm Using CS2 9.0.2 on Powerbook with Cinema Display
Please see Photo (This is a Screen shot seen at 50% viewing in PS)

It's common practice to use the noise filter, surface blur or smart blur (or a combination of them) to reduce the banding effect.