Even so, there are other strong reasons U.S. PC sales dipped in the second quarter of this year and are likely to remain slow in the current quarter, IDC says. These include a saturated market for notebooks, a slowdown in ordering as vendors try to reduce their inventories, and longer refresh cycles among commercial customers. On top of that is the general sluggish economy and low consumer confidence.

"We don't expect PCs using Windows 8 to boost growth significantly until the fourth quarter, which leads to a conservative outlook for the third quarter," says David Daoud, research director for personal computing at IDC.

While overall PC sales dipped 0.1% worldwide compared to the second quarter last year, some individual vendors made significant gains. Lenovo had a 25% increase in sales, bumping it up to No. 2 from No. 3 in sales, IDC says. HP retained its No. 1 spot, but its share of the market dropped from 17.6% to 15.5%. Asus sales jumped 39.8% but it remained in fifth place.

Windows 8 includes a new feature called File History that was explained in detail this week .