Windows movie maker is easy and relatively inexpensive. If you want to do more complex/advanced stuff you could purchase the Adobe Production Premium, which has Premiere, Soundbooth, After Effects, Encore, Illustrator, Photoshop, Flash, and Bridge. That would give you the full gamit of tools to create a great video.
Premiere will be your main working area for visuals, while Soundbooth is the place to develop your soundtrack and compile soundbites. You can use After Effects to put finishing touches, and Encore to develop a good DVD menu.
Tutorials are available through Adobe or at
www.videocopilot.net (very helpful) These programs are relatively easy to learn, especially Premiere and Soundbooth, which is where you will do most of the work.
I would advise if you are going to buy these programs you should put them on a school computer and try and do it with team funds, rather than buy it personally, so it can be a resource for years to come on your team. (also, adobe can be pricey)