The short version:
DLA. Drive Letter Access. UDF packet writing software for CD/DVD.
The long version: Don't do backups with writeable CDs/DVDs if you intend the backup to be unique or available for a long period after it's written. You'll come to find that CDRs vary considerably in their quality and hence the length of time you can expect to retrieve data from it. There's also a considerable difference in burning and reading powers of various CD/DVD writers to consider as well. Be careful!