Dell Inc's personal computer shipments topped Hewlett-Packard's in Q1 as worldwide demand rose because corporations and consumers increased their purchases, two market research firms said. Dell's shipments rose 29% to 7.49 mln units in the quarter, topping Hewlett-Packard's 6.33 mln units, Gartner Inc said. IDC reported Dell's shipments at 7.68 mln units, up 28%, compared with Hewlett-Packard's 6.42 mln units, a 16% rise. Overall demand rose 16.5% in Q1, IDC said. Gartner said the increase was 13.4%. Corporations are now replacing PCs at a strong pace and consumers want to use their PCs for photography and videos, IDC analyst Roger Kay said.