I have a mac book air, have multiple windows open, HDR photo manipulation in Photoshop and 1080P HD movie editing with iMovie, and it never falters (in fact blows my I7 CORE desktop PC system out of the water at work).
SSD is the key, virtual memory with SSD is like having extra Ram, with instant read and write capability. Keep your drive clean, use Cloud based FREE storage systems (dropbox for example) and enjoy the speed of a fantastic PC. I never let my Mac drop below 100gb (easily done!) and it is lightening fast!
Apple does nothing for you....delivers better speed, more reliability, better infrastructure, ssd drives as a standard, lighter system, solid metal casing, multi gesture track pad, retina screen, better and faster OS system, 13 hours battery and less depreciation compared to a PC, and i will still be using the Mac long after any other PC laptop will have gone to silicone heaven, oh and they are a joy to use and super sexy. What else would you like?