Zoron's right... but most of us wish he wasn't. The 64-bit versions of Windows ship with both 32-bit and 64-bit versions of Internet Explorer. (64-bit Windows can still run 32-bit programs.) The most common plugins for displaying interactive multimedia (e.g., videos, weather radar loops, etc.) inside the browser are Flash Player, Java Runtime Environment, and Silverlight. At this point, only Java has a version available that works with 64-bit browsers. Adobe says that Flash Player will have a native 64-bit version for Windows in the next release after version 10.1 (currently in beta). No one outside the company really knows, but it will probably be at least a year. And 64-bit Silverlight... Not even solid spoken promises, AFAIK. Your best bet (and this is what I have done, so I know it works) is to run a 32-bit browser in 64-bit Windows. There is really no performance drop. Besides, the only major official 64-bit browser for Windows is Internet Explorer. Going with a 32-bit browser certainly widens the range of choices you can make.