Changing Host and the Effects on Google

[newsky]

I am about to move a site form one host to another, for various reasons, on of them is space and another is that I used to register sites with the same hoster, and a lot of my (now) critical sites now have the same IP address or are in the same IP range..

I wonder if anyone here has done the same and experienced ranking problems or improvements with Google after the move?

Thanks