Global sales for smartphones are, for the first time ever, overtaking sales of personal computers, an IDC report said.

Worldwide smartphone vendors shipped 100.9 million units in the fourth quarter of 2010, an increase of 87.2% compared to 53.9 million units shipped during the same period last year, according to IDC’s worldwide quarterly mobile phone tracker.

Meanwhile PC shipments were weaker than estimated, up just 3% to 92.1 million.

However, IDC analyst Ramon Llamas said that the two trends are not necessarily related. Consumers usually need both smartphones and PCs as they serve different purposes. Moreover, users are likely to replace their phones more often than they do their PCs.

Falling prices are one of the reasons why smartphones sales are rising. Smart phone sales are also getting a boost from growing interest in Google’s Android software used by many smartphones.

IDC mobile devices technology and trends team senior research analyst Ramon Llamas said Android continues to gain by leaps and bounds, helping to drive the smartphone market and it has become the cornerstone of multiple vendors’ smartphone strategies, and has become a challenger to market leader Symbian.

"Although Symbian has the backing of market leader Nokia, Android has multiple vendors, including HTC, LG Electronics, Motorola, Samsung and a growing list of companies deploying Android on their devices," Llamas said.

According to the report, the top five mobile device vendors were Nokia, Apple, Research In Motion, Samsung and HTC.