Suggestion Needed

The best way is to split the file into smaller parts. Many utilities will prepare this for you and then seam the parts back on the client side once they are all collected and validated.

winrar comes to mind but most any packaging utility will perform this.

 

Not to sound "piratey" but you could start a bit torrent tracker on your server and upload that file through bit torrent....since that's what bit torrent is actually supposed to be used for......

 

Torrents will certainly help cut your bandwidth bills, as downloaders share and share alike, however many people shy away from legitimate torrents for the reason mguindon10 suggests, it seems "piratey".

Many server applications have problems servig files over 2GB - this is one of the reasons for example that only certain Centos Mirrors provide the full DVD Distro's.

I suggest splitting it into chunks - RAR or 7Z it, and if it was me, I would keep the chunks under 600MB incase any of my downloaders wants to burn off the bits onto CD to move it to another machine.