Looking for IDE to start programming CG Shaders.

I have started witting some shaders. First ones were fairly easy to write in notepad but now I need something with a bit more meat.

I have checked rendermonnkey that seems to support CG but it is really old and don't know if it is a good option. On the other hand there exist this FX Composer 2.0 but it seems something that could really distract me from learning shaders because it seems a pretty deep program.

Are there any other possibilities? There's a really nice alternative to write shaders named ShaderToy but just supports GLSL.

Thanks in advance.