No matter what editing sof

No matter what editing software you have it is a very intensive process to edit AVCHD files.

Quad Core processor is highly recommended, version 3 or version 7 doesn’t matter.

If converting to AVI you need to make sure the conversion is to DV-AVI, you are correct that there are many forms of AVI.

Lots of good stuff about editing AVCHD in Premiere Elements is available at the Muvipix Community
http://muvipix.com