New Landlord, Same Lease?

Hi,

I am looking to purchase a duplex in which one side is occupied and the other is not. The current tenants have a lease which does not expire until 12/07, however I would like to lease out both sides to my son who is in college with three roommates starting 7/07. If the current owner sells me the house, am I obligated by law to maintain the original lease, or can I terminate it early without tenant approval?

If not, is it illegal to raise the rate of the rent to a high amount, given a reasonable amount of notice (30 days?) to achieve the same goal?

Thanks

Normally you do take the property subject to the existing leases and the lease terms.