Businesses should hold off on investing in WiMAX until the technology is more widely deployed across the United States and until vendors produce more dual-mode cellular/WiMAX handsets, says a new report from Gartner Research. Overall, Gartner projects that while WiMAX networks in the United States will start operating commercially over the next two years, WiMAX itself will remain a “niche technology” that will best serve emerging or rural markets that don’t already have access to broadband services. One of the big factors that WiMAX has going against it, says Gartner, is that WiMAX networks won’t be able to provide nationwide…