To actually answer the OP's question:

What spending $1200-1500 will give you is better, crisper shifting, lighter frame & overall better components. You'll also go from 9-speed to 10-speed, which means upgrading various components becomes easier. None of this will make you faster, but it will improve the tactile experience of riding a bike.

Also, at your budget, you might want to consider ponying $150-200 locally to get fit for a bike, and then buying a bike from bikesdirect.com (in the $700 budget) or one of Competitive Cyclist's sale bikes if you decide to up your budget to $1500.