iam trying to do the same steps what the user was done before

iam having old iphone 2g 2008, at&t contract phone,( but unlocked using zibri)

it has 1.1.3 version, and 4.X baseband ( not above .26 i belive)

due to some application not able to support 1.1.3, so i would like to upgrade to 3.0 and later 3.1.2 for better performance of my application.

1. i downloaded 0.9.2 redsn0w
2. downloaded 3.0 (iPhone1,1_3.0.1_7A400_Restore)

so can i directly connect with USB cable to Iphone start moding the phone, wth out any problems, am i missing something here.

( why iam asking, i do not like to miss any data or contacts from the phone,)

so i want to make sure what iam doing.

kindly suggest me, or any IRC where i can get good guidance when iam doing this proceedure to co-ordinate if something go wrong