Apple has gone on the advertising offensive with a new series of ads slating Microsoft's huge campaign to support its Vista operating system.

The Apple adverts, featuring the same actors behind its previous 'I'm a Mac, I'm a PC' campaign, have been posted on the Apple web site and the first two are already being aired on television.

The first mocks Microsoft's policy of not mentioning 'Vista' but using 'Windows' instead. John Hodgman's PC character buzzes out the word 'Vista' whenever it is used.

The second Apple ad has Hodgman dividing stacks of money into two piles, one for advertising Vista and a much smaller one for fixing Vista's problems.

Microsoft began a $300m advertising campaign featuring Jerry Seinfeld, but the first two adverts were unpopular and the series was dropped.