Forums are taking off, but I need to change the main URL

[bc_2005]

My main URL now is from my old website which i got rid of, and the forum site I have now has a domain name that is just parked on the previous one. I asked my hosting company if I could have the main domain switched to the domain name of my new website and this is what they said: "We can change the main domain on your account. However, this will cause
you to lose all of your emails and databases on your site."

So is there a way I can do that and not loose all 10,000 + posts and information saved in my forums? my forums grew to 230 members in a weeks time and I didnt get to switch the domain before. what can I do in this situation? I am scared of losing everything