oh to start it off the HV20 is not really HD and even if it was it would be pointless because there are not many HD screen u can have so the quality of the video would always bee brought down.
i was u i would get the trv900 because it is 3ccd and it has manual function and u can get a baby death lens for it (a really nice fisheye lens)
Its relitivly inexspensive for wat it is.
The vx1000 like the one guy sugested b4 has the prolly some of the best audio and colours u can get on a camera. it is also cheap but this is becasue it is fairly old and so there will be no warrenties and it will be harder to fix if it breaks. and it also DOES NOT have a lcd screen (the pop out screen on the camera)
If you want to become a better filmer you should get a camera with the most manual settings as possible (white balance, audio ect.)
IF you want to find out more information about cameras go to www.skateperception.com
they are both very good sites (snowperection.com doesnt have many members yet so join and make new threads)