I am afraid of losing any data (it happened to me on in the past when syncing a smartphone to Windows - lost all contacts)
What is the safest way of doing this on a Windows PC? (The iPhone is also jailbroken - does it make any difference?)
Tell iTunes to sync it as an existing phone, and it shouldn't remove anything. Or, migrate the iTunes library to the new machine, and then sync the phone.
Disclaimer: I haven't tried this on Windows, only on Macs.
From memory if the phone is jailbroken, then it will backup / sync to any computer. However you can plug it in and see - itunes wont go and delete anything without your permission :)
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