I found that most converters do not work very well. I got poor quality images and I must have tried 10 different online an downloaded programs. This route is a little pricey, but you get good software for editing video and it works.
I use Adobe Premier Elements 4 for video editing. I then bought the FLV Importer from Moyea (http://www.flvsoft.com/flv_importer/). This way you can put all FLV's into Adobe then save to any format they make available.
NOT!!! if you want to go from the trial version to the registered version, you must uninstall the trial first and reinstall from the link they send you after you purchase, You cannot just add the registration key to the trial version.