what version are you running now and what one do you want to upgrade to?
I'm guessing he wants to upgrade from v4 to v5.
OP, I would say wait until v5 has matured a little bit. 4-5~ months after "gold" should be enough.
Unless if you're not using any 3nd party addon, check if your addons are available (or should be available) for vB5. Otherwise you'll have just a forum in your site.
ty guys
I would keep hitting the demo and wait until you are happy with the features and performance.
It is recommended you not upgrade your live site to vB5 until the software goes Gold. (And no, I don't know when that will be.)