Pbuffer maximum size

[Fool Running]

I assumed the maximum Pbuffer size was the maximum texture size returned by glGetInteger(), but when I create a Pbuffer of 1024x1024 (maximum texture size reported) and draw to it, it seems to only create a Pbuffer of the size of roughly 600x600 although no error is returned.
Getting the Pbuffer width and height after its created doesn't work either since it just returns what was passed into the constructor.

Is there a way to get the real maximum size of a Pbuffer or the size that was actually created?

EDIT:
I found that there is a way to look up the max Pbuffer size. From the OpenGl spec:

    Accepted by the <attribute> parameter of
    wglGetPixelFormatAttribivEXT, and wglGetPixelFormatAttribfvEXT:

      WGL_DRAW_TO_PBUFFER_ARB              0x202D
      WGL_MAX_PBUFFER_PIXELS_ARB           0x202E
      WGL_MAX_PBUFFER_WIDTH_ARB            0x202F
      WGL_MAX_PBUFFER_HEIGHT_ARB           0x2030

However, it doesn't look like this is exposed in LWJGL (Because these are Windows specific?). Anyone have any ideas?

EDIT2: Forgot to mention, this is on Windows XP with an Intel graphics card.