I'm an ex-nzer IT nerd. Auckland has the biggest range of IT jobs, however there is currently a toss-up between Auckland and Wellington for best wages for IT workers and Wellington is known to be a great place for newcomers to start in.

As far as Auckland goes, there are places like Takapuna which are just outside the city that have companies like telstraclear who should be looking for good IT workers.

You also have a lot of companies in Albany, including 1 of the larger isps which I believe is orcon.

Hopefully that helps abit