I've been a big fan of using Google Chrome on Windows. The Mac beta is also coming along nicely (with the exception of how it runs Flash slowly). I've had to switch back to Firefox after switching to a Windows 7 64-bit system. Using Chrome will freeze the entire system, requiring holding down the power button to restart. After Googling (how ironic) I found this is not a new issue. Shame on Google for taking so long to resolve such a nasty bug.