The new iPad HD Video File Size

I want to shoot short HD videos with the new iPad's 5-megapixel iSight camera. When it comes to HD video, the more space. How much space do you think 1080p HD video will take up? With the new iPad improved camera and 1080p HD video, should I go 32GB or 64GB? How long each video clip can be record as long as you want?The new iPad at 5MP has an average file size of about 1-2MB. Storing 500