I never used Windows Live Movie Maker but the old Windows movie maker (came out for XP) had a certain limit of around 25 minutes before it would choke and die and you ended up not being able to produce any output; hopefully Live has fixed this elusive barrier.
Convertxtodvd is a good program but not freeware. And even it doesn't rerender multiple videos into a single stream if you are trying to put multiple clips together; so they end up as separate pieces on the DVD player all showing up with their own time counter from for example 0 to 5 minutes rather than minute 12 to 17 of a 60 min video.
I actually know these things above because I spent a couple days helping a neighbor with a 90 min DVD for a Christmas presentation for her parents. The movie maker (not live) would chug along for about 45 minutes and then give an error that the files couldn't be located and give nothing. We tried several breaks and ended up with 4 sections under 25 min each that finally didn't kill it. Then I tried using ConvertX2Dvd to merge them on a DVD but ended up with the 4 segmented clips with individual clock counters and a very hard time using forward and reverse or skip ahead because of these segments.
I actually had an old version of Pinnacle Studio that came with my TV tuner which I hadn't installed on Win7 because I hadn't needed it since my conversion. The W7 compatibility center flagged the version I have as "recommended for upgrade" but, as it is not freeware, I went ahead and tried my old version. I pulled in the 4 streams my neighbor had created and told it to rerender the entire project and out came a beautiful 90 min DVD to which, when her parents saw it, they called me over to thank me and her mom gave me a kiss :embarassed:
So if you are interested in buying software to actually create and do your own A/V editing then Pinnacle Studio is a good product and they do offer a free product (w/ registration) called Pinnacle Videospin
that may meet your needs but I've never tried it myself. To create DVDs ConvertXtoDVD is a great paid product for converting many video formats to a DVD (but it does not rerender multiple videos into one).