If you're going to author a standard DVD (vs. just dropping video data files on a DVD) you're going to need to convert any video into DVD compliant MPEG-2 files (YUV 4:2:0, specific resolution, etc.)
Then you're going to need an authoring tool to handle creation of control files, scripts, menus, etc. There are couple of good apps that are commercial - Nero Vision (part of Nero 8) and Ulead DVD Factory (2 flavors, regular and pro). Those apps have provision to handle capture, conversion, authoring and burning (basically everything in one app).
This freeware app - DVDStyler:
http://www.dvdstyler.de/
Is actually pretty good (it's an opensource port), but it doesn't handle MPEG-2 conversion. MPEG-2 requires a royalty payment so you usually don't see that in freeware media conversion apps (it's usually a pay CODEC "add in").
FYI, this is probably the best site on the web for video information:
http://www.videohelp.com/