|You can try uninstalling the drivers to either HD audio controller, IEEE 1394 controller or the 2 entries for the card reader.|
Goto Device Manager, ensure Show Hidden Devices is ticked, right click on the device you want to uninstall then choose Uninstall. Then reboot and see if Vista will reinstall the device to a different irq.
You may have to uninstall them in Safe Mode, and you may have to move the device to a different pci slot before installing drivers for it which would hopefully force the OS to change the irq.
If you manage to get it changed but it still does it, it may be the nvidea graphics card. So try updating its drivers or testing with an older one. Also check for drivers on the disk controllers. See if the stuttering happens whenever the hd is being accessed.
Hope any of that helps.