Shaders.....

i''m not sure why you think OpenGL is ''lagging behind'' D3D.... however on the subject of shaders and OpenGL.

Cg will give you the most range from one bit of code from what i can tell, as it will target any of the Nvidia cards and use the Nvidia extensions to get the best from those cards, be it vertex or fragment shaders you are writing.
It does fall down a bit with ATI''s cards, iirc it can only target cards which expose the ARB_vertex_program and ARB_fragment_program extension, which is def the DX9 series of cards (R3x00/9500 and up), however i''m not sure about before that and afaik it doesnt have a profile to produce code to run on ATI''s version of ''register combiners'' (forgoten the name atm)

OGLSLang, or OGSL, is, as you might know, OpenGL''s native high level shading language, but unlike Cg it is currently only working GFFX and above Nvidia wise and 9500 and up ATI wise, due to it targeting DX9 class hardware.

Personaly, i perfer the OGSL mainly because its native to OpenGL and doesnt require any extra libs. Granted its still got a little way to go driver wise but i like its way of working, althoght i havent had the time to do anything concrete with it as yet (maybe in the next few weeks when i get some time)

I think that GLSL is THE ULTIMATE shading language, due to it''s one very unique feature - the shader get compiled by the driver at runtime, which in turn means the best optimisation.

It''s sad that it has no DX8-class HW support.

apprently the GF3/4 will get support of vertex shaders in GLSL at some point soonish.
I''ve also asked ATI if they plan on releasing vertex shader support for the 8500/9100/9200 and was told they have no plans to atm

Hmm ok ill do some more reseach on Slang and Cg.But it seems slag would be the better choice....