Even as Apple and Microsoft expand into new markets, the computer business remains a big financial driver for both companies. Illustrating that point, Apple reported a 51 percent increase in Mac shipments yesterday, contributing to a big increase in profits. And some analysts suspect that better-than-expected PC shipments may have boosted Microsoft's latest quarterly results, which are set for release this afternoon.

So it's a good time to revisit the trends in PC and Mac shipments. Here are our standing charts, updated with the latest data from Apple and IDC. The numbers show the Mac experiencing significant growth in recent quarters. In comparing that to PC growth, the effect is magnified because the Mac is growing from a smaller base, a sliver of the overall personal-computer market. But it's still an interesting trend to observe.