Just for fun I have produced a set of wallpapers for Blackberry devices such as the Curve 8520/9300 as well as other handsets with a suitable screen resolution
Assuming that your Blackberry service works, why not show it off and let your friends, family and colleagues know you are with giffgaff as a way to recruit them.
The set includes jpegs of 480x360 pixels in various colours with the Blackberry / giffgaff logo
Simply save them to your PC and copy them to your phone and then set as wallpaper
Also see an alternative design