well in theory at least they are, as you say, backups so not essential for the running of the computer.
However it would be nice to know what they are backups of before saying yeah delete them, do they have a name that may be a clue, or even the name of the folder.
Best option if you really can't figure out what they are backups of would probably be to burn them to CD and then delete them, at least then if you subsequently find out you do need them for anything you still have them.