ask for some extension libs of opengl...

I would like to know whether there are some “good” extension libs? I mean the liberary should use conveniently and support as many as extensions(not too limited)…
My VGA is nVidia that support opengl 1.5 and my OS is windowsxp.
Can someone give me some advice? Thanks in advance.

I not exactly sure what you are looking for. If you want a library to make opengl extensions easier to use try GLEW