Hybrid CrossFire on dual pci-e mobo

As a result of a series of upgrades, I am left with an interesting mix of hardware and I am wondering if the following configuration is possible:

On a 790GX chipset mobo with dual pci-e slots, to have a Radeon HD 3450 in one slot, operating in Hybrid CrossFire with the onboard 3300 graphics, driving dual monitors (through the 3450's HDMI and DVI outs) AND a Radeon HD 4670 in the second pci-e slot driving a single display through its DVI port.

I don't think this info is important but the setup I am going for is dual 22" 1920x1080 LCD's for multitasking/productivity plus a 46" 1920x1080 LCD dedicated to movies and hi-def tv via a Hauppauge WinTV HVR-1600. Part of the motivation here is to take as much load as possible off the CPU (Athlon II X4 630 oc'd to 3.2GHz). I've got plenty of headroom as far as power supply and cooling is concerned so that's a non-issue.

Thanks for the help!