North/South Island; How much time between Islands ?

Starting mid February I plan on touring (by car) New Zealand for 3 weeks.
Looking for suggestions how to split my time between the North and
South Islands?

Go to the Air New Zealand site as at the moment, they have special deals for visiting the wineries and links for the NZ Wine Industry which should be helpful to you.,
http://www.airnz.com/default.htm click onto airfare specials.

Like to see the culture, lifestyle, history, scenery and the wineries in Marlborough.

If you like the cities and bright lights - North Island. For scenery that is unequalled elsewhere in the world - try the South Island. Particularly
Malborough sounds, West coast, Milford, Queenstown, Stewart Island, Mt. Cook and heaps of others. Personally I would spend the whole three weeks in the
South Island, as for an Australian the North Island offers nothing new.

So there are now thermal areas & maori culture in Australia, wonders will never cease ;-8