Thanks for your quick response, please.
1) How do I tell buffer underruns and what do I do about them? There seems to be two buffer bars going, I assume one is for the HD and one for the DVD-RW, and the burning does seem to pause while the upper one is moving. The lower one shows 98% a lot.
2) I will defrag my drive tonight.
3) In Device Manager, I have two Primary and two Secondary IDE channels. The HDD and the DVD-RW are in the two Primary IDE channels - although the HD is SATA and has a separate port on the motherboard. Does it matter that the drive is set as primary? In my BIOS, the SATA drive is IDE 3 (master), and the DVD-RW is IDE 1 (master). In the directions, it recommends putting the drive as secondary (master), but that shouldn't make the difference, right?
4) I think the DVD drive is at UDMA 4 and the HD (Maxtor SATA) at UDMA 5. I have the ASUS P4P800 Deluxe, which has two SATA ports as well as two IDE ports.
5) This is the time for full burn only. I've installed the actual speed hack, and the speed goes from 8x to 14x, slowly building momentum through the 15 min burn.
I'll go through the other steps after I hear if any of the above matters.