The longer answer is given assuming that your current data center is utilizing a non-virtual server environment in conjunction with either server attached storage or a legacy thick provisioned SAN. If this is the case, you are definitely in luck. With the improvements afforded by server and storage virtualization I would minimally project the ability to provide an order of magnitude more servers (virtualized) and an order of magnitude more storage capacity (virtualized). Depending on the rate of growth for your business, this could potentially carry you for years to come.