(Reuters) - Apple Inc overtook Hewlett-Packard Co as the world's largest vendor of personal computers in the fourth quarter, helped by booming demand for its iPads, research firm Canalys said on Monday.

In the fourth quarter, tablet demand helped drive the global PC market 16 percent higher than a year ago to 120 million computers, Canalys said.

Excluding tablets, the market fell 0.4 percent from a year ago, said Canalys, one of the first research firms to include tablets in PC forecasts. Other firms have said they will likely follow.

(Reporting By Tarmo Virki; editing by Andre Grenon)