Nearly one percent of internet-connected PCs were running Windows Vista in February, according to research from Net Applications, making it the sixth most-popular operating system.

The operating system was released to businesses last November, and only made its consumer debut on 30 January, but Net Applications analyst Vince Vizzacarro said it’s proving a hit on new PCs. However, the upgrade market has yet to bite, according to Vizzacarro.

“It looks like the market is buying Vista on new PC purchases, but there isn't a significant percentage of people upgrading existing PCs. I expect this trend to continue through the rest of 2007."

Vista's exact share was 0.93 percent. Windows XP continued to lead, with 84.3 percent, followed by Windows 2000, with 4.8 percent. Mac OS X on PowerPC machines had 4.3 percent, while newer Intel-based PCs running OS X had 2.1 percent.

"The big question is if and when are the masses going to switch?" said Vizzacarro. "While Microsoft was late to market with Vista, Apple's taken advantage and is now up to a combined 6.38 percent market share.”

Some analysts have predicted that despite Microsoft's intention to spend half a billion dollars marketing Vista, conversions from XP won't be the norm until 2009. Even Microsoft chief executive Steve Ballmer has said that some Vista sales projections have been overly aggressive.

Statistics for the first week of February were mixed. Current Analysis found sales of PCs - with Vista preinstalled - were up 173 percent from the week before. PC sales were also up 67 percent from the same time frame in 2006. But Current Analysis itself pointed out that the sales leaps were exaggerated partly by slowing sales as retailers and OEMs wound down their XP-based inventory.

By comparison, NPD Group found that first-week sales of boxed copies of Vista were down 60 percent compared with first-week boxed copies of Windows XP five years earlier. Neither group has released statistics of Vista sales in subsequent weeks, though NPD analyst Chris Swenson is expected to release first-month retail sales of the new OS soon.

This story adapted from an original article by Eric Lai Computerworld US.