GOM Player - Much better for playing vids than WMP with little things like frame by frame advance, moving about through the vid, creating loops, screen capture abilities, etc. Comes with its own codecs and is worth a try. Just give a right click in the vid area to see how much it has to offer. It can also play Flash video files (flv's).
Returnil Personal Edition - There are a number of virtualization solutions out there, but this is one of the easiest in terms of use. When you turn on the session lock, from that point on, every change made to your primary partition is undone with a simple reboot. It's great for testing software (that doesn't require a reboot), engaging is risky activites, etc. It gives the option to create a virtual disk during install, so if you only have one logical drive you can use the virtual to save to save things you may want to keep if you're currently in a session lock. Version 2008 is currently in beta and will give a few more features.