No need to upgrade the motherboard. H61 supports even the newest ivy bridge i5's with a BIOS update, downloadable from Gigabyte.
Depending on the power supply model, you likely don't need to upgrade that, either. If it is of even average quality, you can run a high end video card on 500W just fine.
GTX660 (or radeon 7850) would be decent video card updates, but what are you trying to gain? Is the 6850 struggling in games now? It's a fairly powerful card as is.
I want a better performance , the GTX 660 2GB is a great Card ! It gives better Performance than 6850 , and the motherboard can't expand the 660 GTX , because of the DVD rom's wires , the video card will hit the dvd rom's wires , I don't know what to with that
If you can help me , I will be so happy and thankful