Welcome to the Apple Discussions. If you drop your current hosting service then you will drop the other services they provide and I assume your two email addresses are included.
If your site is a commercial or ecommerce site I would not change your host for MobileMe. It's slower, more unreliable (due to the high server side overhead software to support the social networking aspects of MobileMe), there's no ear to ear customer support and it's against the Terms of Use for MobileMe accounts (although I've not heard of any site getting bumped off for that reason).
You could keep the current account to use the email and still host the site on MMe.
Happy New Year