Apple continues on its steady march to the top of the technology heap, according to the latest PC market share reports from Gartner and IDC. Both firms have released preliminary sales estimates for the third quarter showing impressive year-over-year growth for Apple just as the company's stock posted record highs at just over $300. The overall PC market is also up slightly both domestically (about 3 percent) and globally (about 9 percent), with Lenovo and ASUS in particular starting to gain on rivals Dell, Acer, and HP.

In the US, market leader HP mostly held steady year-over-year, commanding a quarter of the PC market here. Dell continues its steady decline, dropping a few points down to 23.4 percent. Somewhat surprisingly, low-cost netbook and nettop maker Acer dropped a couple points as well. More or less as Intel stated during its quarterly earnings report, Gartner analyst Mikako Kitagawa contributed Acer's and Dell's drops to a softening consumer market.

"The third quarter historically is a strong consumer quarter, led by back-to-school sales," Kitagawa said in a statement. "Consumer mobile PC demand, driven by low-priced notebooks, including mini-notebooks, slowed after very strong growth the past two years."

That dip from Acer allowed Apple—posting a nearly 20 percent unit sales growth—to capture 10.5 percent of the US market and to slide right into third place in the US. The company has been doing especially well with its notebooks for the last few years, but also had a couple updates to its iMac, Mac mini, and Mac Pro desktops recently. The third quarter is typically Apple's best, and you can see the cyclical trend over the last couple of years. Some analysts predict that Apple will report a record 4 million Mac sales in total in its upcoming quarterly report next Monday.

Apple is also riding high from the introduction of the iPad earlier this year, which many analysts attribute to breathing new life into the struggling tablet market. Market research firm DisplaySearch noted that counting sales of iPads, along with notebooks and notebooks, would place Apple as the number four portable computer vendor globally.

The iPad's influence on the overall consumer PC market, especially in the US, should not be discounted, according to Kitagawa. "Media tablet hype around devices such as the iPad has also affected consumer notebook growth by delaying some PC purchases. Media tablets don't replace primary PCs, but they affect PC purchases in many ways," she said. "At this stage, hype around media tablets has led consumers and the channels to take a 'wait and see' approach to buying a new device."

Looking at historical data for US PC market share, both Dell and HP have leveled out over the last few quarters despite being down year-over-year. However, both Apple and Toshiba have steadily increased while Acer has taken a dive in recent quarters. With all the focus on tablets, this trend could continue if consumers are lured towards the iPad or any number of promised Android, Windows Phone 7, and BlackBerry tablets.

Looking at the global market, positions haven't changed in the last few quarters. However, the top three vendors—HP, Acer, and Dell—showed some negative market share growth year-over-year. (To be fair, Dell's was a rounding error—flat is better than what the company has been doing recently.) Meanwhile, the next three vendors—Lenovo, ASUS, and Toshiba—posted significantly better than average gains for the quarter. In particular, Lenovo is closing in on Dell, and sitting just two percentage points away from grabbing the number three spot globally.

The overall positive growth for the PC market is a good thing, but it will be important to watch the trends as consumers increasingly move to more mobile and handheld computing using tablets and smartphones.

Note: The data used for this report comes from preliminary figures supplied by both Gartner and IDC. Figures for the third quarter US and worldwide PC sales were averaged from both data sets. Historical trend data is compiled from Gartner.