okay, this is rather unpleasant. I erased the disc (quick), and tried to re-burn the iso, during the verify phase, I got an error --
I 09:31:40 ImgBurn Version 2.3.2.0 started!
I 09:31:40 Microsoft Windows XP Media Center Edition (5.1, Build 2600 : Service Pack 3)
I 09:31:40 Total Physical Memory: 3,405,916 KB - Available: 2,144,036 KB
W 09:31:40 Drive R:\ (FAT) does not support single files > 4 GB in size.
I 09:31:40 Initialising SPTI...
I 09:31:40 Searching for SCSI / ATAPI devices...
I 09:31:44 Found 1 DVD