Olli's guide to ensuring that you don't get slowed down during migration
http://dnn.ebsfaq.com/EBS/Setup/disableadvancedNetworkcardfeaturesusingCMD/tabid/1848/language/de-DE/Default.aspx
To turn off the advanced networking features like EnableRSS (Receive Side Scalling) and/or TCPChimney which can be somehow slow you setup very much down to the speed of a turttle:
Press Shift & F10 during first setup wizard page on every box:
netsh int tcp show global
netsh int tcp set global chimney=disabled
netsh int tcp set global rss=disabled
netsh int tcp show global
Read the complete post at http://msmvps.com/blogs/bradley/archive/2008/09/29/olli-s-guide-to-ensuring-that-you-don-t-get-slowed-down-during-migration.aspx