Like Masterjun said, you can animate the images in Vegas by
keyframing them, setting their position/rotation/scale at certain points and letting the computer fill in the rest. It's a lot like animating objects in a 3D modeling program like 3DS Max or Maya, except in 2D. You can keyframe anything you want: text, images, even videos I believe.
A good example of what you can do with this method is
the Game Grumps intro. The heads, text, and blue circle behind the text are all keyframed. Obviously your video will be a lot longer, but you might find all the little animations fun to make, especially when you get to send objects spinning wildly off the screen or instantly shrinking.
See also
this editing tutorial by the Grumps' (former) editor. It goes at a casual pace and demonstrates visually how to keyframe with a Vegas-like video editor.
Also, when you're ready to save your video, try to encode it with something like the
XVID codec to save disk space and uploading time. Or you could compress your video file with the program
HandBrake.
And here are some screenshots at frame 
