Copy 100gb+ file over LAN?

[Max Kipness]

Hopefully this is not too off topic.

I have a server in which I'm creating an Exchange Information Store
backup using ntbackup. The .bkf file it creates is 112GB. My goal was
first to rsync it over to a local linux server, and then rsync just the
changes over the internet to another linux server. I do this with other
Exchange .bkf files (in the 4GB to 20GB range) and it seems to work well
only transferring the changes over the internet.

My usual method has been to map the Windows 2003 drive on the local
linux server and then use rsync. When trying this with this system, the
transfer speed is super slow from the beginning, at 6 mbit per second on
a 10/100 mbit network. If I try the copy using smbclient and get, I
actually get 60 mbit p/sec for the first 30gb, then it seems to slow to
6 mbit. A regular cp does basically the same thing as it starts out fast
and then slows all of a sudden. This obviously will not be very
practical as on the local copy I usually would copy the entire file each
night. At that rate it will take days.

Any suggestions on how to copy a 100gb file over a local LAN quickly? Or
what copy/transfer command might keep the same quick throughput during
the entire transfer? Or could there be something wrong on the network?

Thanks,
Max