Blu-Ray on a non 1080p. TV?

I have a Sony 1080i. or 720p, TV 50-inch Flat Screen. I wanted to get the $299.99 Blu-Ray Player. Would my TV make any deference in Blu-Ray and DVD. Could I also Buy a cord that would make it better. So far I no that my TV has no HD Input but has it in Blue,Green,Red,Yellow. So if so what cord could I buy. Give Details and you will get picked.