answer:I use Gentoo and it’s 64-bit. Mostly. I use a 32-bit version of Firefox for Flash, although I’m not sure I need to; I seem to remember a 64-bit version of Flash being available. For torrents I use Transmission and never had a problem, other than not liking Transmission. And I don’t have a problem with USB transfers, either. Gentoo is a sourced-based distro so if you’re used to downloading packages and having them ready to go you’ll be in for a shock while you wait for everything to compile. I’ve never noticed a distinction between 32-bit and 64-bit tarballs, though, so I’d say it’s likely that a large portion of source code will compile on a 64-bit processor with little or no changes (unless they changes are wrapped up in the source).