According to Raven2260's link above installing the hybrid OS per the excellent instructions linked is a requirement to support BBM 5.0 since the hybrid OS updates files needed to run the newer version. In others words, the only way to run BBM 5.0 on an 8330 or 8830 is to install a hybrid OS that includes the needed files unless/until a 5.0 version is released by RIM.
How simple is it to do this? I'm not too phone savy but I want bbm 5.0, can anyone help me please
It's not very hard at all. Skunkd has laid out some fairly straight forward instructions for installing the hybrid OS. I am currently running the hybrid installed from the link below, and I was able to install BB Messenger 5.0: