If at first it doesn't work - turn it on. If it still doesn't work, plug it in!
Perhaps an external HDD for daily backups, and DVD-Rs for monthly? Remember, I don't think you would be backup up your OS, just your stuff.
When I get a desktop, I'll have it either with 3 HDDs or 3 partitions - #1 = OS, #2 = Apps and #3 = Docs. Only then really need to backup #3, which would only get large with media, such as lots of pics, music or video - and those don't really change much - just get added to, so an incremental backup would decrease the need for excessive storage space (1 full backup, then each backup afterwards would only be the changes - ie and files that have changed, any new files, etc)