It is easier to just take it to AT&T, have them save all your stuff, and then have them re-set to factory settings. The store can re-load all your contacts, and Marketplace stores all of your apps in "My Apps"....after re-set, open the Marketplace and go to "My Apps" and download the ones you want re-loaded.
The downside is that some of your contact info is lost. To alleviate this, put all your contacts on GMail and then sync your phone. When you re-set, all your contacts are at GMail and automatically reload along with your calendar (if synced with GMail).