I found this a activewin - you might already have this setting, though
You might find that Windows doesn't refresh Explorer instantly. If you have created a new file, you might have to wait a few seconds before the file shows up under explorer. And if system resources are low, Explorer sometimes won't even refresh by itself! If you are tired of pressing F5, launch the registry editor and scroll to HKLM\System\CurrentControlSet\Control\Update. On the left pane, double click UpdateMode. Change the binary value from 01 to 00. Restart and Windows will refresh at a faster rate.