Hi -

I just learned about this from a client.

Vista has a setting called "Receive Window Auto-Tuning Level". Having it turned on (the default) can dramatically slow connections to "older" (pre Server 2008) servers & many "older" routers. Disabling it sped up response in an app (all workstations on this small network are Vista Business) at least 300% - maybe more.

http://blogs.msdn.com/wndp/archive/2007/07/05/receive-window-auto-tuning-on-vista.aspx

Most of you probably already know about this, but thought I'd pass it along -