HD4200 and XFX HD4850

I think hybrid crossfire is only possible with amd chipset mobos and the HD 4000 series is not capable of it....hybrid crossfire is only possible with low end cards....if at all u want to crossfire a low end GPU with an integrated one u wont be needing a bridge.....

That is correct. There are only a specific number of GPUs that are supported in hybrid crossfire - I believe they are the 3450, 3650, and maybe the the 3850. The 4xxx series was not supported, last I checked.