If you want you can send me the scene, i'll try and see what i can optimize for you settings-wise. Plus i got a quad-core system, if its faster then yours it might slash the rendertime a bit?

By the way, you can also use the lens blur filter in photoshop, in combination with a depth mask, to manage your DOF.
Did you have TA on in this picture?

Another option could be to render the image in 2 passes. One where your objects render with TA and the light has no volume.
And another one where your objects are black, TA-less, and you can render the volume light with that, so you get a seperate layer with just the volume light.
Then you can combine the two in photoshop, which even allows for some tweakings of the overall look of the volume light, without needing to re-render.

--
Ray

(_/)
(='.'=)
(")(")This is Bunny. Copy and paste bunny into your signature to help him gain world domination.