Apple computers are encroaching into the PC market space, capturing over 6 percent of the US computer new sales research indicates.

According to market research firm Gartner, Apple shipped 1.035 million Mac units in the U.S. in the fourth quarter of 2007 for an increase of 227,000 over the fourth quarter of 2006. Market share increased a full percentage point, from 5.1 percent to 6.1 percent.

A similar report released by IDC shows Apple shipping 1.058 million Macs.

The results put the Cupertino , Calif.-based consumer electronics maker in at 4th place behind Hewlett-Packard, Dell and Acer to close out 2007.

On Tuesday, Apple chief Steve Jobs introduced a new addition to its line of notebook computers, the Macbook Air which may aid continued growth into the new year.

Available in 2 weeks, Jobs hailed the Macbook Air as the world's thinnest laptop, but it is unclear how well the product will fare against competition, and even other Apple products.

To us, there may be too much overlap with its existing MacBook and MacBook Pro, analyst Shaw Wu of American Technology Research said.

But then again, AAPL has proven fairly adept with product placement, most recently with iPhone and iPod touch where there has been minimal cannibalization despite overlapping functionality.

While Apple's increase outpaces the gains of all other computer manufacturers in the US, Hewlett Packard took the overall lead with 18.2 percent market share.

Hewlett-Packard recorded a 30 percent increase in personal computers sold last year, eclipsing Dell which shipped 1.7 percent more PCs. Dell's share slipped to 14.3 percent.

A total of 271.2 million computers were shipped in 2007, up 13 percent, Gartner said.