"Touch machines are actually selling above expectations," said Bob O'Donnell, a program vice president at IDC. And that means supply shortages. "Some vendors are actually facing shortages because touch panels are in limited supply. Vendors are saying they can't get as many touch-based machines as they would like to meet the demand that they're seeing." Rhoda Alexander, an analyst at IHS iSuppli, echoed O'Donnell's comments. "We've talked to a number of PC makers that are having trouble obtaining touch panels and some of the vendors I've talked to said they can't keep them on the shelf," she said. And Microsoft has said as much. Tami Reller, chief