With iPod shipments coming in lighter than expected, other digital music rivals and companies that supply parts for the iPod also took it on the chin in after-hours trading. In recent trading, shares of PortalPlayer ( PLAY) were off $2.11, or 7.8%, to $24.89; Sigmatel ( SGTL) shares were off 8 cents, or less than 1%, to $13.61; and SanDisk ( SNDK) shares were off $1.82, or 3.5%, to $50.10. At least with PortalPlayer, the selloff might be a buying opportunity, said the second portfolio manager. Some 90% of PortalPlayer's sales are tied up with iPod products, and the company will likely benefit from the demand for the nano, he said. While Apple's iPod shipments may have disappointed bulls, the company's results were nothing to scoff at. iPod shipments might not have been as high as some were hoping, but they still rose 5% from the company's third quarter and 220% year over year. Meanwhile, the company's line of Macintosh computers posted strong sales as well, with unit shipments up 5% sequentially and 48% from the fourth quarter a year earlier. And thanks to strong sales from its retail stores, overall revenue rose 4% sequentially from its third quarter and 48% year over year.