Best Flash Drive Backup Utility?

[User Name]

I'm wondering if there is some program that can backup (or synchronize) content of the flash drive at the background (completely invisible, as system process), so when somebody want to safely remove flash device, he can, even if all content is not copied yet. So, i'm looking for backup flash program that is totally invisible to users, except he will copy content of flash drive to for eg. C:\WINDOWS\flcnt ... is there any prog that can do this?


Thanks...