In fact, the answers that say there's no Nvidia Crossfire equivalent are wrong. However, the GeForce 7050 motherboard GPU described in the question is too old to support it (and it wasn't a very successful technology anyway). It's called Hybrid SLI, and this article describes it in some detail. It has 2 modes: one like Optimus to save power, and one to increase performance.
NVIDIA Hybrid SLI Ready Motherboards:
- nForce 720a MCP
- nForce 730a MCP
- nForce 750a SLI MCP
- nForce 780a SLI MCP
- GeForce 8100 motherboard GPU
- GeFOrce 8300 motherboard GPU
- GeForce 8200 motherboard GPU
The GPU in question would be on a 610i or 630i chipset (source), so it's not supported.
+1 @Enigma and @JourneymanGeek, Your answers are good except that they're both technically incorrect. And as for the other suggestions, Lucid Virtu is pointless since replacing the mobo in this case would get rid of the mGPU the OP is trying to use as a boost, Lucid Hydra is for mixing PCIe GPUs (not a PCIe and a mobo), and Optimus is for saving power not boosting graphics (as well as having the same issue as Virtu).
@Enigma as Journeyman Geek pointed out, no, I don't think you can run dual monitors with a mGPU that old.
tl;dr: You can't run these two GPUs at the same time, but not for the reasons in the other two answers.