You can download .526 from here
. Don't worry, its an official RIM upgrade. Just fill in the required info, download it to your computer. Then,
Do a backup of your device first, using Desktop Manager > Backup. Close Desktop Manager upon completion and unplug BlackBerry.
Download the OS file to the PC then install it to the PC by running (double clicking) the file you downloaded.
Go to c:\program files\common files\research in motion\apploader and delete the file named "vendor.xml."
Plug in BlackBerry and double click on "Loader.exe." It's located in the same place as the above vendor.xml file was in.
enjoy the new OS.