Hello. I am using a MacBook Pro 2010 (i7, OS 10.6.3). I sometime use Fusion 3.1 to access to Windows Vista 64-bit partition under BootCamp. I read that Snow Leopard is defaulted to 32-bit. 64-bit can be enabled by pressing 6 and 4 during startup. Is it safe to try out the 64-bit kernel? I worry that if there is a compatibility issue such as problems with drivers or softwares, my system may get messed up even when the system returns to 32-bit kernel next time it boots. Also, is it safe to use Time Machine to back up the system during the trial period? So far, TM has been backing up my laptop running 32-bit. I wonder if switching the 32-64 bit kernel back and forth will mess up the TM backups. Thanks.