I need a software that can backup a large directory (~25GB) to multiple DVD discs. It sounds easy enough, but I'm having a hell of a time finding anything that actually works. I tried comodo backup, it sucks. I tried AceBackup 2, it didn't work either. Both of them will write to one DVD, then stop without asking for a new disc.

I need incremental support, and the files to be backed up non-encrypted and not compressed. What is there that actually works?

I would probably use a second hard drive (Internal/External/NAS/SAN/RAID/Other) and backup to it using DeltaCopy or Robocopy.
DeltaCopy http://www.aboutmyip.com/AboutMyXApp/DeltaCopy.jsp
Robocopy GUI http://technet.microsoft.com/en-us/magazine/cc160891.aspx

Acronis True Image might also work but isnt free.

If you need to burn the data to disc, I know ImgBurn has a 'Write Queue' mode but that is only for image files.