As i said in my earlier post,U have the money go for the av500.Its much better thasn av420.It has a 4' screen, a camera attachment,usb host capability,more space,the software looks cool etccc
on the other hand if money is a constraint then go for av420 .U will miss out the screen and the usb host capability but it is more reliable considering the reviews and ratings it has recieved.I wont say Av500 is unreliable but av420 is more reliable.