Yes, you can have a mouse shadow without QE, but it's a lot more likely that one has QE without a mouse shadow. New computers can easily have QE without having the mouse shadow. The shadow is completely unrelated to graphics card age, amount of VRAM or even Quartz Extreme.
The mouse shadow issue discussed here only applies to the standard mouse cursor. The spinning wheel and You Can't Copy That Here cursors use similar shadowing techniques, yet these shadows work correctly on all setups. Thus the issue with the basic arrow cursor is probably a bug.