Converting from Colour to black and white?

I picked up a colourized version of an old Laurel & Hardy movie for dirt cheap and was wondering if there is a way of removing the colour and restoring it back to the way it was intended to be viewed in glorious b&w? I know how to rip the film, but if anyone knows of software that will basically greyscale the film so I can re-burn it I would be greatful. Thanks
Tony

 

u need a nle (non linear editor) like premier or vegas that can do the trick for sure.

However before resorting in the purchase of these programs, check virtualdub if it has any filter that can do the trick for free

 

there is a encode in grascale option in xvid

 

Thanks to both of you. I will check out Virtualdub