Note: Please see this blog post for the most updated recommendations on this subject.
I am sure many of you might have seen the issues that can be caused by the Windows Scalable Networking pack and incompatibilities with certain NIC drivers, as previously mentioned in http://msexchangeteam.com/archive/2007/07/18/446400.aspx.
As of yesterday, there is a new High Priority Windows update available that will turn off of the Scalable Networking Pack features once it is installed. If you have Windows Update setup to receive updates automatically, this update will be downloaded and automatically installed. If you need to manually apply the update, you can reference http://support.microsoft.com/?kbid=948496 for more information as well as a link to the download. Note: Once this update is installed, you must reboot your server for these changes to take effect.
I would highly recommend applying this update to all Windows 2003 SP2 servers to help alleviate some of the connectivity issues that can occur as a direct result of having the Scalable Networking Pack features enabled, and some incompatibilities with NIC drivers that we have seen.
In Windows 2008, these features are disabled by default and can be enabled if desired.
Have a great day!!