Space needed to host the virtio windows drivers, which cannot be included in the official Fedora distribution due to requiring Windows to build (though source is GPL). Total space needed is estimated at less than 200M. Expected layout will be a repository for each currently supported host Fedora Release, as well as a directory for direct download of the source, ISO, and floppy images. Number of users is somewhat hard to determine, but expected to be a large percentage of users running windows guests on Fedora kvm. For more background see http://lists.fedoraproject.org/pipermail/advisory-board/2010-January/007892.html