PC makers are struggling with declining sales as tablet computers and even smartphones encroach on their territory, a U.S. market research firm says. Research company IDC said that PC shipments totaled 86.7 million units last quarter, a drop of 0.1 percent from a year ago and far below IDC\'s projection of 2.1 percent growth, CNN reported Monday. \"The challenge now is that PC demand in the United States, Western Europe and the developed world is slowing down,\" Bob O\'Donnell, vice president of clients and displays for IDC, said. \"Who out there now needs a PC and doesn\'t [already] have one?\" The overall state of the economy isn\'t helping, analysts said. \"It certainly seems that the industry as a whole is in a slump,\" Craig Stice, senior principal analyst for computer platforms at IHS iSuppli said. \"Bottom line is still the economic conditions worldwide.\" Counting tablets as PCs makes the outlook for traditional desktop and laptop computer makers even worse, experts said. Under that measurement Apple was the top PC seller worldwide, British-based Canalys, which counts tablets 7-inches or larger as PCs, said. That bumped Hewlett-Packard from the top PC vendor spot. During the second quarter of 2012 Apple sold just 4 million Macs but moved 17 million iPads, CNN reported.