PC utilities: backup setups

backup setups

I'd like to set up some backups for my system - I want to keep an up-to-date copy of my documents on a flash, and periodically do a full system backup on an external. I'm planning to use acronis trueimage for the HD backup, but what do you recommend for managing backups to a flash drive? I tried using briefcase (it sucks), and deleting/recopying is both a time waster and possibly dangerous (if my comp were to crash after deleting). What's a good piece of software to see what's changed and alter only that on a flash (i.e. if I delete 10 files, move 5, and add 10, the backup software will see this and mirror these actions on the flash)