RAW Photos From iPhoto to Camera to Photoshop

Steph

I have a Nikon D5100 and Photoshop CS5, which uses Camera Raw 6.0. Camera Raw won't let me open my raw photos from iPhoto. It lets me with photos taken with my D3000, but not my D5100. I downloaded the plug-ins for 4.6 and 6.6 updates, but I don't know how to install them or use them. How do I open single and multiple RAW photos in Camera Raw? It doesn't seem like it should be this complicated. Please help!