I have an iphone 3g with version 2.2.1 (5H11)
modem firmware 02.30.03

I want to update the firmware to 3.0 or higher but first things first.I need to back up my apps and data, so I need to get an app backup but Cydia starts "downloading data" freezes and crashes.So can I just reinstall Cydia again or will it loose all of my apps and data when I do this? Or what is the best way to do this.
Thanks