Hybrid crossfire requires a motherboard that supports it, without knowing what motherboard you have, I can't say if yours do support it or not.
It entails you to use the onboard video GPU along with a discrete lower end GPU.
Here is a quick glance at what hardware is used by Tom's editor: source
<-- CLICK HERE for info
The bottom line is it's not really worth the hassle, HD4770 or (if your on tight budget) HD4670 are under $100 and will blow away the hybrid crossfire performance.