Plenty of good suggestions here.
But just a word of caution, it sounds like you are producing a video for commercial use - for a company or whatever. If so, you can't just slap a CD track on there, you will need record company permission to do that. Or you can use Library music, no permission needed but a licence fee to be paid through PRS (which would also apply if you did get permission to use a record co. track)
Of course, no problem if it's just for personal, non-commercial use (Youtube or whatever) although there is a lot of negotiation going on about that too..
Oh - just read your post more carefully - Graduation video - shouldn't be a problem with that...
