patch KB931770 can makes the file copy 3 times faster than before in vista.

i had copied 90GB data from my laptop to a mobile disk while i need reinstall the computer, it takes me more than 3 hours to complete. the copy speed varies from 500K to 27MB, when copy bulk small files, the speed is around 2MB. why 500K? most hard disk nowadays can run copy at speed around 20MB.
after repartition and installed the Vista, i need copy data back to the laptop. but the speed still remain low. sometime it stop response and often it pop ups: "windows doesn't have enough memory to copy the file" then the copy process interrupted. after restart computer and try copy again, it still has same problem. my laptop has 2GB RAM installed. and there is no other application open. obvious its a bug with famous Microsoft brand.
searched over Microsoft.com i found a path KB931770,
the description is locate here: http://support.microsoft.com/kb/931770

since it is not a security fix, this patch dose not install by default in Windows Update.
it didn't say it can improve copy speed.
but after i manually installed the patch. the error message has gone and the copy speed improved from 2.5MB to 9MB, lot faster.

compare to windows xp, Vista copy files much faster.