I use leopards timemachine (and carboncopy), a custom set of cron/rsync scripts, manual archives, and de-ja-vu. I generally backup to online storage, external hardisks, shared disks at relations houses, and archive to optical media kept in fire safes.
I would never trust windoz to do anything mission critial (however I have used Acronis Trueimage in the past with good results), I prefer Linux for backups but do also use osx
I've had too many harddisks fail on me over the years to be fooled into thinking that just one external disk backup is enough. Double and triple redundancy all the way
Steve