Your DC's internet connection would all depend on the services and requirements of your customers needs.
If you are going to run a couple of low traffic hobby websites then you will not need such a big leased line... Whereas if you are offering an online backup solution to companies then you may require more bandwidth.
The best solution would be to find a leased line provider that will allow you to increase the speed quickly and effectively. If you have a line installed you will want a quick and easy way to upgrade that line when demand increases.
This will not be sufficient to run a data center. In US you would need atleast 10 Gig from multiple upstream providers. Setup a multihomed environment to offer good experience to your customers.
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