Don’t worry about the g/b firmware aspect - conversion is very straightforward. The only issue might be warranty support if you have any problems with the drive. You should probably use CDSpeed and burn a few test discs before doing the conversion, just in case.
You have what many people (including myself) consider to be one of the best burners available, particularly if you stay with +R media. It’s not perfect, but firmware updates are regular, and they are gradually fixing the few minor issues that remain.
You are correct - it would be a PRO when you switch the firmware. But note that this “PRO” name is just marketing hype - meaning that it can burn some of the double-layer media at 4X instead of the minimal 2.4X. Since this media is still extremely expensive, it probably doesn’t matter one way or the other.
I recommend you keep the burn speed for CD writing down to 24X instead of 40X. It will handle both probably, but my scans show the 24X speed is a bit cleaner. For DVD’s, feel free to overburn most 4X +R discs to 8X and most 8X discs to 12X - the scans are mostly great at these higher speeds. I’m not convinced that the 16X speed is completely ready for prime time yet based on the quality of some of the scans that I’ve seen, but others may argue this.
If your system is an AMD motherboard with NVidia nForce IDE drivers installed, beware. Many people have had problems with XP, even with the latest firmware (myself included), in particular with XP hanging on boot. My recommendation is to go with the Microsoft drivers and stay away from the nForce drivers altogether.
Good luck with your new drive and have a GREAT Christmas!