Re: NV20 FBO support ?
The site delphi3d.net has a list of all opengl extensions and can show which card supports it and you can also get a list of the extensions supported on each for a specific driver version. The database is reasonably up to date. Unfortunately there's no recent report from a geforce3 card, though geforce4ti cards seem to support it. As the geforce4 (ti) is more or less a slightly improved geforce3 you card might support it.
Note that you can allways check if an extension is supported using glxinfo:
glxinfo | grep GL_EXT_framebuffer_object