The Intel 945G does not support any shaders AFAIK. any opengl application intending to use shaders should check the opengl extension string for “GL_ARB_vertex_shader” wich is probably not availble on tis IGP.
The fact that you GL_VENDOR is not intel suggests to me that you do not have the most recent drivers. You should go to the intel website and download the latest drivers for your hardware to be sure. According to the chipset you provided, you should be looking for the driver for the 945GZ driver.
If you want software emulation, there is mesa3d.org which provide MESA. On Windows, it does software emulation and currently supports GL 2.1
You need GL 2.0 at minimum for GLSL.
Of course, it is not worth it. Just by a 30$ video card such as a Geforce 8.
The 945 is actually a ps2.0 capable part, with the caveat that it has no hardware support for vertex shaders. D3D9 can run vertex shaders in software emulation and pixel shaders in hardware on it with performance competitive with a GeForce FX series card, so long as you don’t stress bandwidth or fillrate.
I reckon your options are to either go for HLSL or get better hardware.