As in previous years, our 2011 Buyers’ Guide comes to you as a downloadable PDF file that can be viewed on your Mac or PC, iPhone, iPod touch or iPad. We’ve created separate versions, two optimized for computers and iPads, the other tested and ready for iPhones and iPod touches. Rather than trying to read the huge book in Safari, we strongly recommend that you download the entire PDF and store it in iBooks, which lets you enjoy it offline…