You can try the P-3 500MHz w/ 512 RAM, with ABSOLUTELY every other program, AV, Firewall, etc. shutdown and disable/disconnect from the internet, etc....and defrag your HD, and empty your temp internet files, but juggling 4GB's of data en route to the DVD, and the burning process is demanding.
I don't know where the actual system performance cutoff is, but you might be able to squeak by. Make sure you are running either Win2k or XP with the NTFS file system due to the DVD sizes.
Just out of curiosity, I burned a CD-R image (not DVD!) with CloneCD and ran system information and Task Manager performance graphs while burning, and took a screen shot. I was suprised to see so CPU/Memory demands as shown in this jpg of my desktop.
I have an Athlon XP2700+ (that is overclocked), WD-1800JB Hard Drive, 1GB of Corsair XMS PC3500 DDR (fastest available for Athlon) in an Asus A7N8X NF-2 mobo with all the latest hardware, and XP-Pro firmware and software updates.