angleproject is your best bet. Check out which exact 965 card you have from here (search for 'intel gma' in wikipedia), which also lists the OpenGL support version for these cards. It might take a couple of months though before you can use angleproject to accelerate your WebGL application.
I have a slightly newer 4500MHD, and I have the same problem. WebGL works on Firefox 3.7a4, but fails in the later versions a5 and a6. I had to use the latest drivers from Intel which claim to support OpenGL 2.0. The Microsoft drivers don't ship with OpenGL support.
I have reported a issue in the Firefox https://bugzilla.mozilla.org/show_bug.cgi?id=570474. It looks like support for Intel cards might be fixed by the time the releases are in beta.