Backing up the phone data

[Incubated]

I thought this was easy and straight forward enough, but i managed to screw it up. When i flash a new rom, it seems to set up active sync all over again, and makes new accounts. I want to flash the 2.5 juicy soon but i dont want to keep losing everything again and again, but i am not sure how to back up the files that i need? do i just copy files from my mobile device and over write when i reflash? this active sync doesn't seem to do anything for me