http://digital-photography-school.com/rule-of-thirds
check that out, it should help. It helps everyone get away from taking the usual centered image.
Enjoy the t1i. Its a great camera. Wait till you start getting deep into photography, its gonna get expensive and turn into a sickness, not unlike our hobby with these cars.
id also recommend this book:
http://www.booksamillion.com/product/9780470521281
will definitely help you get started as well as give you some great tips for shooting. Digital Photography for Dummies is also a great choice as well. Best of luck wiht the new camera
--jeff