One time BitTorrent download

I know about BitTorrent, but I have never used it since it tends to be mostly used for illegal download of movies and software. Typically whenever I see a legitimate use for it (Linux distributions) there is also a regular download option so I haven't had the need for a client until today.

There is a large (500 MB) file I want to download that appears to only be accessible via BitTorrent.

For a one-time use, is there an online resource that converts the torrent to a normal HTTP no-special-client-software download?

If not, what is an easy to use and light client to install/uninstall on Windows XP for a one-time use?

μTorrent would be a good option. Free Download Manager is a download manager with BitTorrent support, you can't go wrong with either of them.

Remember that most BitTorrent clients might need to use ports for incoming connections, and if your router doesn't support UPnP you might have to do it manually.

See this post explaining how to download any torrent through your browser (using the site http://torrentrelay.com/). One of their suggested services is torrent relay.

What browser do you use? Opera comes with built-in client for BitTorrent and Firefox has some BitTorrent plug-ins. I don't know how about Chrome though.

Yes, there is an online way to convert a torrent to HTTP downlodable.

You can use the ImageShack Torrent Drive.

Downloading the file(s) pointed in the torrent can started and can run unattended. When it is finished download can be done using a normal HTTP transfer.

The ImageShack torrent download service is free.