I can't speak for exactly which package/solution to go with, but I can tell you that you should ALWAYS have some form of removeable media as backup and that you should ALWAYS have backups that are offsite.
Never count on a fixed solution for your backups. The reasons are many. What if a virus/errant app simply deletes the files. What if a disgruntled about-to-be-ex employee decides to rm -rf your archive directory. What if there is a fire in your building over the weekend. etc.
Regardless of whether you choose tape (AIT, DLT, etc) or optical (CDR, DVDR, etc) is up to you and your budget. But absolutely do nightly backups and absolutely take one of those backups around every week or so and take it off site. Also a good idea to occasionally test your backups by doing an occasional restore, you don't want to find out that your backups are junk when you REALLY need it.
