Those are rar files and need to be unpacked.
The free 7Zip will do that. After install right-click a rar file and select 7Zip and then extract and all the files will extract to reveal the content you want.
http://www.7-zip.org/
Virgin has announced new plans to throttle bittorrent, but those should take place in mid-2009.
http://torrentfreak.com/virgin-media-to-throttle-bittorrent-users-081216/
However, the Azureus-Wiki lists them as interfering now and also shows that they limit bandwidth for users with high traffic...