Part of Apple's ability to defy -- sometimes quite dramatically -- the ongoing slump of traditional PC sales may be due to a slow-growing but increasing acceptance of Macs in the enterprise. Needham & Company analyst Charlie Wolf has highlighted the growth in a note to investors using data from the September quarter, showing that sales of Macs to US businesses has nearly doubled over the past year, from 5.4 percent in fiscal Q4 2011 to 9.3 percent in the most recent quarter. While sales of PCs to the business sector were down 13.3 percent year-over-year, Apple was up more than 21 percent in th