Some resources you may find useful, depending on what you want to do.
Note that if you are looking at spending serious time on image or video tasks for professional purposes, you probably need to look at professional-grade software and also gain some professional skills in image design or film-making. These tools are aimed at the sort of things students and teachers typically do as part of another subject area.
SumoPaint http://www.sumopaint.com/app/ – a very nice Web2.0 tool, very similar to Photoshop. It’s free and as its entirely online you don’t need to install anything on your computer. You can set up an “account” if you want to save things online, or just save to your computer. Has inbuilt help at http://www.sumopaint.com/help/
Irfanview http://www.irfanview.com/ – Free simple image editor – needs to be installed but should be available to all students as a simple resize/resample/convert type tool.
Image Resizer PowerToy http://www.microsoft.com/windowsxp/Downloads/powertoys/Xppowertoys.mspx – resize one or many image files with a right-click – avoids the inevitable “5Megabyte image in a Word document” problem ….
Microsoft MovieMaker free download at http://www.microsoft.com/windowsxp/downloads/updates/moviemaker2.mspx , help at http://www.microsoft.com/windowsxp/using/moviemaker/default.mspx
How-tos at http://www.ecentre.education.tas.gov.au/C5/Movie%20Maker/default.aspx (need DoE username and pwd offsite)
Simple video editing based on the standard timeline model
Audacity http://audacity.sourceforge.net/ – free audio editing tool, has to be installed. Also need to download the LAME MP3 encoder if you want to export to MP3