I would seriously consider buying Sonic Fire Pro, it is very easy to learn and, depending on which cuts or discs you buy to suppliment the application, you will have a diverse collection of audio to back your video. Sonic Fire has just come out with their 4th version which includes a new feature
"Mood Mapping" which may insure that your version is not duplicated by someone else. I was a beta tester this last Fall for them and was impressed by the versitility of the new feature. Unfortunately, older Smart Sound discs cannot take advantage of the new feature but still work just fine within the program itself. The type of music you use can make or break a sequence. All Sonic Fire music is copyright free so no problems there as well.
You might also want to investigate music by Music Bakery, Riverside, Music 2 Hues and the many other copyright free music libraries out there. If you are a Mac person, you should take advantage of their Soundtrack application which allows you to create your music yourself. You just need to have a feel for it but do not need to be able to play an instrument. I love using Soundtrack as it is fun and creative; however, it does take an investment of time to create the piece you are hoping to make.
Steve B)