Here's my scenario: MacBook Air (late 2011) OS 10.7.5 (although it's bumping to 10.8 once this is resolved) Parallels, with Snow Leopard (10.6.8) installed Dropbox on the Lion (primary) side; not on Parallels/SL side yet What's the best way to set up Dropbox in the Parallels (SL) environment? There are about a dozen large folders I need to access from both operating systems---it's imperative they remain in sync with the office computer. My best guess: Install Dropbox in SL, then use Selective Sync to limit what shows up there. My big worry: Those folders are huge. Won't this double up on the amount of disk space used? Any wisdom would be deeply appreciated. Can't find a thing on the Dropbox site, other than people having problems with installs already in place (I'm hoping to do this right from the start, not do it wrong, then contend with damage control). Thanks in advance!