I just bought the full version of Vegas Movie Studio Platinum Edition and I can confirm that, just like trial version mentioned previously, it seems to be able to use the AVCHD files from my Canon HG10 camcorder.
I purchased it from Amazon, opting for the CDs and box version, rather than the download, and it was considerably cheaper than going though Sony.
I decided to go for the CDs because on many occasions I have had computer troubles and have lost software that I had downloaded from the Web. For example, I had an excellent little ico editor which was useful for creating favicons. Unfortunately it was on another machine and is gone forever. I can’t remember its name, so if anyone knows of a good favicon.ico editor, please let me know.