select write image file to disc, and i would suggest using 2.4x speed.
Also, if your planning to burn the iISO file onto another disk afterwords, select write image file to disk, select the ISO file, then put in a blank DVD-R disk (verbatims advised) and burn the file onto the disk at 2.4x speed.
I tried it at 6x and...
I 22:22:46 ImgBurn Version 2.5.0.0 started!
I 22:22:46 Microsoft Windows XP Professional (5.1, Build 2600 : Service Pack 2)
I 22:22:46 Total Physical Memory: 523,760 KB - Available: 127,596 KB
I 22:22:46 Initialising SPTI...
I 22:22:46 Searching for SCSI / ATAPI devices...
I 22:22:46 Found 1 DVD
Log:
I 18:56:05 ImgBurn Version 2.5.0.0 started!
I 18:56:05 Microsoft Windows XP Professional (5.1, Build 2600 : Service Pack 2)
I 18:56:05 Total Physical Memory: 523,760 KB - Available: 76,876 KB
I 18:56:05 Initialising SPTI...
I 18:56:06 Searching for SCSI / ATAPI devices...
I 18:56:06 Found 1 DVD