Camcorder Buying Guide Grid Using A HD 720p Camcorder, What Size SD Card Should I Buy?

Using a HD 720p camcorder, What size SD card should I buy? - camcorder buying guide grid

With a video camera in 720p HD, SD card, what size should I buy?

I think the purchase of a TH1 Sanyo Xacti VPC-HD camcorder, and I know what size to buy SD card ...

I would like to add approximately 2 hours 720p, so the size should I expect?
Is there a kind of rough guide to follow?