At one site I support I've setup a couple of 2008 R2 servers and joined them to an existing 2003 domain. When transferring a 2GB file from 2003 to 2008 R2, the speed is pretty decent, however 2008 R2 to 2003 is extremely poor. I'm talking 2.5MB/s poor and the servers are connected at gigabit.
I've upgraded the Intel drivers on both 2003 and 2008 R2 servers and this did improve transfer speeds slightly, but they were still far too slow.
On the 2008 R2 servers, I then disabled IPv4 Checksum Offload and transfers from 2008 R2 to 2003 are considerably quicker and a lot more acceptable. Any idea(s) why this is happening? Is there anything else I could/should tweak? Many thanks!