Your .blackberry.net email can not be set up to forward, nor can it be set up to be viewed anywhere else. It is restricted to just the BlackBerry platform and device so you would need to migrate to another email provider if you made the switch.
Posted from my CrackBerry at wapforums.crackberry.com
Just register some free email and forward there for now. It's a bad habit to bit tied to some such "non-transferable" email. Come on, with all options. Get GMAIL -- you still can have PUSH mail for GMail on Android, Blackberry and iPhone!