The Radeon HD 7660D is a little more powerful than the Radeon HD 5570. See benchmarks in the following link.
http://www.anandtech.com/show/6332/amd-trinity-a10-5800k-a8-5600k-review-part-1/2
Richland's iGPU (Radeon HD 8670D; I think) has been estimated to be anywhere between 20% - 40% more powerful than the Radeon HD 7660D. A 20% increase means it will be equal to or a little better than a Radeon HD 5670. At 40% it should be somewhat close to a Radeon HD 6670. The chart below should give you an idea of the relative performance.
Source:
http://www.techpowerup.com/reviews/AMD/HD_6670/22.html
The Radeon HD 7750 is basically equal to the performance of the Radeon HD 5770 / HD 6770 (same card, different name).
Tossing Intel into the mix, the Intel HD 3000 would be equal to the Radeon HD 5450, while the Intel HD 4000 would be a little slower than the GT 520. The upcoming Intel HD 5000 in Haswell mobile CPUs (laptops only, not for desktops) is rumored to be about equal to the Radeon HD 7660D; which means it should be a little more powerful than the Radeon HD 5570.