Re: Just a little Question regarding my BlackBerry Curve 8520..
To change the OS, the best way is to make a backup and/or sync your contacts and calendar with Outlook or Google.
Then wipe it with Jl_cmder (see the FAQ) and then load a specific OS for your device - i.e. since you have an 8520, you must load an 8520 OS. See the yellow sticky at the top of the 8500 section for the OS and instructions. For earlier releases, see the RIM website.