One of the main complain I had about Vista is the slow file copy or move operations. It seems that it is the new "Remote Differential Compression" who is the culprit.
To turn it off go in Control Panel / Programs and features / Turn on or turn off Windows features and uncheck "Remote Differential Compression".
I found out that Vista TCP/IP "Receive Window Auto-Tuning " slows network access too.
To disable it, open a command prompt and type:
netsh interface tcp set global rss=disabled
netsh interface tcp set global autotuninglevel=disabled
and reboot .