Please remember that bittorrent was NOT designed to be a p2p warez network. Its simply a internet protocol designed to distribute sending large amounts of data between large amounts of people.
It's like saying FTP is a p2p network. I've got news for you the entire internet is a p2p network, when you connect your computer it's as much as a part of the internet as
www.anandtech.com is.
Actually it was originally intended for distributing Linux cdroms. It can get very expensive for a non-profit to distribute cdrom images thru a ftp server when you have to pay for the amount of bandwidth you have to use.
For instance in the recent release of Fedora Core3 operating system they moved 37 terrabytes worth of information in a few days. That's impossible with normal internet protocols.
Anyways for Bittorrent to work you need to have a large number of people seeding. Otherwise it's not any more effective then ftp websites.
What I do when I need to send a large file is I setup a Apache web server and simply e-mail a link to whoever I want to download it. I ask them to send a e-mail back when they have downloaded it successfully.
They have Apache web servers for Windows if you don't have a Linux/BSD/whatever OS laying around. You also need to have a port exposed to the internet.
Usually if it's a very big file I'll split it up into 10meg sections. With a 4gig file that would be around 400+ files or so (usually something that big would be a entire directory of stuff in a tar file).
With scripting it's realy easy to do once you know how. That way if they can't download it all at once, then can download it in sections. If any part the connection gets interrupted then it's only about a maximum of 10megs that has to be redownloaded.
Plus if you compress a big file and any part gets corrupted you loose that entire file, but if you split the file up and compress each section then if any part gets corrupted then you only loose that section and not the entire file.
I recently used this method to backup my home directory because I am going to reformat and change my computer around drasticly. I ended up with 4558 10meg files.... That way I can easily copy them and burn bunches of them to cdroms or copy them to a few different harddrives (because my home folder was on the biggest drive I own.)
With scripting you just make the computer do all the leg work.
With Windows you can split them up into "rar" files or whatnot using GUI tools, but if it's a big file it'll probably just be easier to just send them a DVD with the information burned on them thru the mail.