For work I'm running parallels and XP pro using CAD software on a 2.13MHz 2009 MBA, and I get the spinning wheel a lot lately when mail and safari with flash is running. I've found it's the 2GB of RAM that's filling up so I've switched to Firefox. It's much better now, but still a bit clunky compared to new. Will it be worth the extra power boost of an i7 be useful? Also worth the hit on heat and battery? (why is there a heat and battery hit,? does the i7 idle at a higher clock speed?) I am sick of windows and OSX upgrades making perfectly stable and fast machines slow with the upgrades, making you buy new machines.