TIPS: Configure your Firewire Port (IEEE 1394) for proper operation of Sound Card in WinXP SP2

These days almost all the proffessional sound card interfaces are designed for firewire (IEEE 1394) port. Firewire port is considered to be more stable than USB 2.0 port (this is my opinion - others may differ). But people face problems also with firewire port if they have Windows Xp with SP2 installed.
There is an article "Performance of 1394 devices may decrease after you install Windows XP Service Pack 2" if you want to check on microsoft's site.  The performance drops because Windows XP SP2 changes 1394b ports to S100 speed. So if you connect a sound card which is designed to run at S400 speed will not function properly since the data transfer rate has dropped considerably.
To solve this problem you need to edit/modify your registry entry as mentioned below:
WARNING!! - Only make changes if you know about registry. Backup your registry before attempting any change since it could leave your system unbootable if any mistake is done.
1. Click Start, click Run, type regedit, and then click OK.
2. Locate and then click the following registry subkey:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\ PCI\1394_hc_hw_id\1394_instance_id\Device Parameters
3. If the SidSpeed value does not exist in the right pane after you click the Device Parameters subkey in step 2, create it. To do this, point to New on the Edit menu, click DWORD Value, type SidSpeed, and then press ENTER.
4. Right-click SidSpeed, and then click Modify.
5. In the Value data box, type one of the values that are shown in the following table, and then click OK.
Value Speed
0 ------ S100 speed
1 ------ S200 speed
2 ------ S400 speed (default value)
3 ------ S400/S800 speed (Windows XP Service Pack 1 [SP1] value)
Note If you try to use a value that is larger than 3, SidSpeed will use a value of 0 (S100 speed).
6. Quit Registry Editor.
To locate the FireWire controller information, follow these steps:
1. Open Device Manager. To do this, right-click My Computer on the Start menu, click Manage, and then click Device Manager under System Tools. You can also click Properties under My Computer, and then click Device Manager on the Hardware tab.
2. Locate your FireWire controller in the IEEE 1934 Bus host controllers section.
3. Right-click the FireWire controller entry, click Properties, and then click the Details tab.
4. Click Device Instance Id. You see a string of letters and numbers that is similar to the following:
PCI\VEN_104C&DEV_8020&SUBSYS_00D81028&REV_00\4&19FD8D60&0&60F0
The information between the two slash marks (\) is the “1394_hc_hw_id".
“VEN_104C&DEV_8020&SUBSYS_00D81028&REV_00” is the hardware ID in this example. The information that follows the second slash mark (\) is the “1394_instance_id”. “4&19FD8D60&0&60F0” is the instance ID in this example.
If you are confused do not attempt yourself - instead consult some computer technician.