Here's a registry patch to allow Nero to show its exact burning speed, moment by moment, that might be useful for you:
First make sure Nero is SHUT DOWN or it will overwrite this change.
Next, click Start->Run and enter Regedit to launch the registry editor.
Go to the following place in the registry:
HKEY_CURRENT_USER\Software\Ahead\Nero - Burning Rom\Recorder
The window pane to the right should have about 20 or so entries already in it. But chances are that the value "ShowSingleRecorderSpeed" is not present. To add it, right-click in a blank area in this window pane and from the popup menu select "New" and then "DWord Value". This will give you a new entry with the default name "New Value #1". Rename it to "ShowSingleRecorderSpeed" and set its "Value Data" to a 1. The Base can be either Hex or Decimal, since a 1 is the same for both.
Close the registry editor and restart Nero. Begin burning a DVD and Nero will tell you the current burn speed (in the place where it normally just gives you the 4X/8X/12X/16X selection) as soon as it clears the Lead In. This will work for CD burning as well.
I really like this because it shows me exactly what my burns are currently doing from a speed point of view.