How much continuous HD video is possible in Nikon 3100?

I'm going for Nikon 3100 DSLR so that I can have still and video through same camera. I want to come out of handling two cameras, one for still and one for video. I want to know how much continuous HD 1080p video is possible in D3100 camera. Is it possible to take video for say 30 minutes, if I put right memory card? I learned some where that it can take only 5 minutes clips, so I'm confused.

According to Nikon.com, the maximum video record time on the D3100 is 10 minutes. They didn't break it down further for resolution or quality settings.getting a bigger card won't help. The bottleneck is the speed that the camera can store on the SD card. Instead it captures all video on its internal buffer memory. When that is full, recording stops and you have to wait 10-15 minutes for the buffer to clear out before shooting again. This is a common problem with this class of camera.