Everytime I do pretty much anything with my DVD-drive, my ISDN connection dies. First all the transfers just slow down gradually, and then I get disconnected altogether. I have an LG DVD-drive and a Telewell ISDN card. Windows XP Pro SP1. 700 mhz, 640 mb, 80 gb
With a 700 mhz processor, I think you made a typo with the memory. A processor that slow would max out at 512mb so I'm guessing you meant to write 64mb. You definitely need to add more memory to your pc as multitasking is using up your systems resources so shut down any other programs that are running at the same time.
You shouldn't be doing anything with your PC while burning especially with your specs. Burning requires a substantial amount of resources so the less extraneous load the better.