Actually, the answer of whether you can crossfire the integrated video adapter with a stand alone video card depends on the model of each. Some configs are compatible.
What make/model of motherboard are you using?
What make/model of video card do you have?
I have an ASUS motherboard with a Integrated ATI Radeon™ HD 3000 GPU,
and added a gigabyte AMD Radeon HD 6450, i have the AMD FX 6100 6 core cpu