upgrade iphone 3gs 3.1.3 to 4.01 help!?

Phaze

New member
what is the best possible way to upgrade from 3.1.3 without losing any data..

can i simply back up 3.1.3 via itunes, then restore to 4.01 then restore back up from 3.1.3?

i have tried this sometime ago it gives me error restoring it.. how do i do this.. easy way pls!
 
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