Bit,

Now that we have you comparing AVCHD to HDV, which is a good start, we'll going to let you in on a dirty little secret, the camera lens is going matter far more than which HD codec you use. Also the person operating the lens and how well that person understands lighting and exposure.

You need to be comparing specific cameras models, not formats because you really want to judge the whole system, the lens, the sensor and the codec all contribute to picture quality.

Both the new HDV cameras and the new AVCHD cameras are going to give you images that blow away your old footage. Probably to the point, where you won't be able to see any issues with either format. Workflow, capture and ease of editing are probably better points of comparison, because both offer great picture quality.

Here's some questions:

What computer do you intend to edit on? What are the specs for memory and cpu, etc?
Does capturing from tape poses any issues for you because A. you shoot a lot or B you need to deliver video quickly?

Do you have an HD TV?