Why would you need WMV? That's the worst choice you could make; a proprietary codec controlled by one company. Most standalone players can't even recognize it. You should be using mpeg2 because that's the native format for DVD. Most players will also handle mpeg1 as well if you want to fit more video onto a disk and aren't worried about the picture quality.
Have a look at avidemux. In spite of the name it's a general multimedia transcoder that can handle lots of formats. It isn't too difficult to use either. Just make sure your output falls
within the specs for DVD playback and you shouldn't have any trouble.
If you're not stuck in graphics mode, there are some good cli tools also. I prefer to use transcode myself, outputting to mpeg2enc.
I also recommend dvdstyler for authoring the dvd menu system. Some players may be able to play back a disk with raw mpeg files on it, but it's usually better to have a properly authored disk.
