No can do on the boot screen. That is burned into the firmware.
And since you use a Mac (hopefully OS 10.5.5 or better), you can only update the OS to an official release by your carrier. To do otherwise requires a PC.
There is no "pure BB" OS. They are all modified by the carriers to include items specific to that carrier.
Don't suppose you know what the situation is with Skype? Some say you can, some say theres a genuine app, some say it's only for US customers...annd... well, some simply say no....
__________________ Never Hold In Your Farts. They travel up your spine and into your brain... That's where you get crap ideas from