When you've got some free time, some free computers and server machines, create a network with a server attached to each computer and then each computer attached to a switch, and then try playing one of the following games:

• Uplink: Time trial type hack, and only works when using a line, tree or star network). Choose one server to be the hack target, and another to be the log target (must be in the middle of the network when using a line network). Lock the target server down with a proxy and a tracer (usually a user using Netstat ), and allow public access to all areas on the log server. Bounce through all other servers on the network, and then break into the target, delete a specific file and get out in the fastest time possible. Time doesn't end until you have deleted the logs from the log server.
  
• Trivia: One computer and server is assigned to a single user (must use fully connected mesh network). Each user must hack into the other servers and acquire a text document containing answers to a trivia quiz. Your own server contains one of the answer sheets too, so nuking your own server when you have all the trivia answers written down is the key to winning.
  
• Team Deathmatch: Partner up with a friend. Servers are armed with a bunch of junk files, and two "golden tickets" (text files hidden within other files, requiring hex editing to retrieve) which are hidden in certain files (usually .zip or .rar files with passwords). Wipe every single file and retrieve the golden tickets to win.
  
• Virus Roulette: Turn-based or not, depending on how far you want to take the viruses. First user to bluescreen loses. Rules basically stat you cannot send any viruses which directly cause a bluescreen; it must be the result of the user trying to interact with the virus.
  

Enjoy the fun reinstalling your OSs!