Not sure about siping or snow, but on ice you're pretty well screwed
either way, studs or chains are the only thing that'll do much on that.

I thought siping was mostly for high performance tires for track use?

Siped tires can provide better traction on slippery surfaces, however
the downside will be lower tread life and higher road noise.  Because
the blocks will be sliced, the car may also feel less steady, or
squirmy on dry pavement.

In my experience the 960 is a well designed road car that handles well
on wet and rainy conditions with a good set of all season tires.  On
snow it is an entirely different matter.  The rear wheel drive
configuration combined with the low road clearance means the car will
lose traction easily, even with the optional limited slip differential.
My suggestion would be to buy a set of snow tires for winter use and
sipe those if needed.  Don't sipe the tires that will be used in
non-snow conditions that will represent 80% or more of your driving.

thanks for the posts. sounds like snow tires are the way to go. cheers,
art