Currently in the world of Microsoft 64-bit computing browsers do exist but many supporting "add-ins" are either not written yet or are still in testing. Although the uk:anon service fully supports 64-bit browsers, many media players e.g. adobe flash player do not work yet. So, if you'd just like to use the browser then everything should work just fine.
We will regularly update this page as and when applications that support 64-bit Microsoft computing are released.
The only way to have a "full-media" browsing experience on a 64-bit operarting system is to use a 32-bit version of your favourite browser.