The First question you should ask urself is why do u backup new files so often?
what i do is: I create a folder somewhere else on my pc, and backup whatever the file is necessary to be backed up, and just copy the file over. The backup utility in windows does NOt only backup ur files, but also ur settings and maybe ur registry (could be around 100MB, it depends on ur sys).
and when ur backup file reachs 600mb, then put them onto disk once.
Multisession recording always works for me, and cd recording is not a new technology anymore, any bugs gotta be fixed by now (use the latest driver and software to avoid any old recording issues).
Hope that help!