I am using Any DVD Converter Pro, it's really amazing program. It can rip DVD and convert all kinds of video format, including WMV, FLV, RM, RMVB, AVI,MKV,MPEG-1, MPEG-2 and so on, to Nokia MP4 files.
What you need to do is just add the video files and choose Nokia N-series mpeg-4 movie as output. Bitrate, Video size and so on can be adjusted according to your need.
With this program, files for iPod, iPhone, Zune, PSP are also available. Youtube video can also be downloaded and converted at the same time, you just need to add the URL to the program.