There's a free and legal site called Zamzar.com that converts video, audio, images, and documents into practically any format you want. You simply upload the file and type in your email address, and Zamzar will e-mail you a link to a web page where you can download the converted file to your computer once the conversion is ready (which most of the time is finished promptly). The page is only avalible for 24 hours though, so don't leave it waiting.

The best part is that it works for not only files on your computer, but also will convert practically any form of media directly from the internet. For example, it is now possible to convert a video from YouTube into a format that you can put on your iPod. The possibilities are endless; you can even convert the video files into audio files if you ever had reason to. And like I said before, its completely legal and free. Zamzar now will allow you to create and account for a cost, which among other privilages, allows you to save the conversion files on the site so there is no 24 hour rush. I've used the site a several times now, and I have yet to have a probelm. I've put the link to the site and some extra info and FAQ's below. Enjoy!

http://www.zamzar.com
http://www.zamzar.com/faq.php (FAQ's)
http://www.zamzar.com/conversionTypes.php (Conversion types that the site supports)
http://blog.zamzar.com (Blog to stay updated on the site's newest features)