How to render with alpha channel background transparency?

I’m creating a new logo for my website and I want to save the render as a PNG image with an alpha transparent background that I can import into GIMP… right now whenever I save there is a gray background color. I just want it transparent. I set it for transparent background but it still comes out gray.

Are you using Cycles or Blender Internal renderer?
Cycles: Enable an image format that allows RGBA for alpha inclusion. Choose ‘Transparent’ under Film.
Blender Internal: Change the Shading to ‘Transparent’ , and also choose a format and enable RGBA instead of RGB.

ok thanks I’ll try that. I just use the internal render, not too familiar with cycles