I rebuilt my laptop this week (it was time) and I ran into this issue again, so I’m documenting it here for my next rebuild.
When I installed Windows 7, my external Firewire hard drive (Seagate 500gb) is slow, for whatever reason, but there is a fix. You can revert to the legacy driver. (!) I’ve seen a significant reduction in the time it takes to copy files. I found this answer here: http://social.technet.microsoft.com/Forums/en-US/w7itprohardware/thread/65cb7a25-2a84-4875-aa27-b084537e8da1
Here are the steps outlined in that news group post:
1- Click the Start Button, type devmgmt.msc in the “Start Search” box and press Enter.
2- Expand the "IEEE 1394 Bus Host Controllers" node in the device tree on the right hand pane
3- Right click the host controller node select "Update driver software ..."
4- Select "Browse my computer for driver software"
5- Select "let me pick from a list of device driver on my computer ..." and Check the box before “Show compatible hardware”.
6. Choose the second option---1394 OHCI Compliant Host Controller (Legacy), and click next to update the driver.