Slow file transfers or network performance with server 2008. If you are having either of these issues you can try to disable a new function in Windows Vista/Win7/2008 called auto-tuning.
Auto-Tuning allows the operating system to continually monitor the routing conditions (bandwidth, network delay, application delay) and configure connections (scale the TCP Receiving Window) so as to maximize the network performance.
However, I’ve found (and read online) that certain NICs and switches do not understand this new protocol and it ends up slowing things down.
You can find information on how to disable this feature here:
There is an automatic “fix it” download that you can run there if needed.