Khoi’s dilemma with finding an online backup solution for his 400GB of data. There’s some good discussion in the comments with many recommendations for [DropBox](https://www.dropbox.com/), [Backblaze](http://www.backblaze.com/indexc.html), or [Jungle Disk](http://www.jungledisk.com/).
[My approach for backing up](http://shawnblanc.net/2008/02/bulletproof-backups/) is to keep it simple, and keep it safe. At my home I’ve got a TimeCapsule/TimeMachine backup, and run a nightly SuperDuper clone to an external. At my work office I’ve got another external that I clone weekly.
Having an off-site or online backup is important because, as Khoi says: *”Fire or theft would leave me as helpless as any less-conscientious computer user, rendering all my self-congratulatory local backups worthless.”*