The booming popularity of tablets has been a mixed blessing for Asus. The Taiwan-based electronics vendor makes takes a hit each time consumers opt for tablets over the laptops and netbooks it makes. At the same time, Asus is investing in tablets, unveiling four models at the Consumer Electronics Show in January. Most of Asus’ tablets won’t launch until later this year, however, when a glut of other tablets from companies ranging from Motorola to Research In Motion to HP will also be on sale.