I suspect there is a strong correlation between the price/performance curve referenced in a WSJ post below and the sales trends...
Computer shipments rose this summer at the fastest rate in nearly two years, and Hewlett-Packard Co. pulled still farther ahead of Dell Inc. as the world's largest maker of PCs, two technology research firms reported Wednesday.
Sales of portable computers drove much of the 15.5 percent increase in global PC shipments from July through September, especially in Europe, according to research firm IDC, based in Framingham, Mass.
p.s. note that Apple Mac growth is roughly the same, according to this related IDC summary