Two out of three IT administrators at large organizations with Macs and PCs said they expect to see an increase in the number of Macs this year, according to a newly released survey by the Enterprise Desktop Alliance.Tom Cromelin, spokesperson for the Enterprise Desktop Alliance, says the survey shows "a green field of opportunity to educate people" about how to manage a Mac-PC environment in the enterprise.Enterprise Desktop Alliance, a group of software developers who've bandied together to deploy and manage Macs in the enterprise, surveyed 322 IT admins about their Mac-PC environment. Enterprise Desktop Alliance members include Centrify, Absolute Software, Group Logic, Web Help Desk, and most recently IBM.The key finding is that 66 percent of respondents said they expect to see more Macs at their companies. This figure is slightly down from last year's survey, which showed that 74 percent of respondents had planned to increase the number of Macs.Not everyone shares Enterprise Desktop Alliance's enthusiasm for Mac growth in the enterprise. "Our stats do not show Apple's major uptake in the enterprise market," says Gartner analyst Mikako Kitagawa. "Apple's share in the PC market has been less than 1 percent in the last several years and has not changed."Nevertheless, survey respondents said employee preference, productivity and ease of technical support are driving Macs into the enterprise. Macs also come on the heels of the iPhone. That is, some users want a Mac because it's more compatible with their iPhone. (The Enterprise Desktop Alliance survey was conducted prior to the announcement of the iPad.)As more Macs make their way into the corporate environment, IT admins will have to deal with an assortment of challenges. In last year's survey, Active Directory integration topped the list of challenges fronting Mac deployment with around 60 percent of respondents citing it as an important issue. In this year's survey, six issues were cited by 60 percent or more of respondents."There's more emphatic interest" in cross-platform issues, Cromelin says.Critical issues in order of importance are: security, file sharing between operating systems, client management, backup and data recovery for Mac files, Active Directory integration, application compatibility, configuration consistency, cross-platform help desk and knowledge base support, and standard management utilities for both Macs and PCs.But companies are getting better at Mac support, says Frank Cabri, vice president of marketing and business development at Centrify, a management software vendor. Sixty percent of the survey respondents said they already have unified support for both Macs and PCs. "There's a realization in some of these companies that they do have tools today," he says.Tom Kaneshige is a senior writer for CIO.com in Silicon Valley. Send him an email at email@example.com. Or follow him on Twitter @kaneshige. Follow everything from CIO.com on Twitter @CIOonline.