Draw a picture in Paint. Train your creative skills with the build-in Windows program Paint. It's a lot of fun and you can create drawings to use with email invitations, birthday cards etc.
Change your Desktop/Wallpaper Find a cool new wallpaper. You can find a few here or surf the Internet for a cool wallpaper. You can find instructions for how to do that here
Add a Cool Screen Saver! You can find many very nice screesavers on the Internet. One of the better ones is the one that comes from "Cozi". it will allow you to have your own photos rotate as your screensaver in a nice Look & Feel
Play a Game! RuneScape is one of the better Free games. But be careful! It's said to be VERY addictive ;-)
Do an online Puzzle! If you like puzzles, you may find a few online Puzzles here to have fun with. Try it - it's actually fun to do.
Watch a Video or listen to Music on Youtube On Youtube you can watch videos or listen to music other people have uploaded. You may be able to find your favorite music or your favorite actor.
Write down and save your favorite recipes You can use any text editing program, you have. If you don't have any of the fancy text editors, Word or Works, you can always use the build-in text editor Notepad or Wordpad.