Change computer's shut-down images
These images are in fact camouflaged 256-color bitmap images (renamed to a file with a ".sys" extension) with a size of 320x400 pixels.
The files are:
c:\windows\logow.sys (Please wait while Windows is shutting down)
c:\windows\logos.sys (it is now safe to turn off your computer)
To change them, simply open them in an image-editing program and replace them with whatever image you like (taking into account that they must have the right dimensions and the right number of colors, and that their width will also be stretched when you see them on your screen).
Changing the logo shown when Internet Explorer 4 loads
The Internet Explorer 4 animation is actually a sequence of 28 256-Color images whose dimensions are 38x38. To replace this animation, simply create a 38x1064 image containing the 28 images you want. Then make a copy of the image, resized to 26x730 (there is one animation for the normal view; the other is meant to be displayed fullscreen (<F11> key).
To make Internet Explorer 4 use the animation(s) that you created, open the registry editer, go to the branch HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\Toolbar
and then create (or modify, if they already exist) BrandBitmap and SmBrandBitmap (the big and small animation, respectively) and set their values to the filepaths which point to the respective animation files.
Turn off animated windows
When you resize or close a window, there is a short "fading" animation. If you'd rather do without this effect, you can turn it off by editing the registry. Go to HKEY_CURRENT_USER\Control Panel\Desktop\WindowsMetric, and by right-clicking in the righthand window, you can choose the command New -> String Value. Enter the value MinAnimate, and then edit this value by right-clicking (Modify) and setting it to 0.
Making Bitmap (BMP) image icons into thumbnails
To make BMP image icons into scaled-down versions of the images themselves, edit the registry by going to HKEY_CLASSES_Root/Paint.Picture/Default-Icon. Then replace the value Default by %1. Note: This will use extra system resources.