I'll challenge you on that, let's e-mail a few game companies like Rockstart North, Microsoft/Bungie, and Blizzard (random companies off the top of my head) and let's see what they say. I'm pretty sure that once you own the game, you can do whatever you please with it. I know creating backups of it is legal so let's e-mail them and find out.. =)
No need to call. Look at the end user license agreement that came with the game you installed. In my experience, games have a great deal of anti-piracy protection, and are very difficult to copy. Not impossible, but more difficult. However, it goes beyond the scope of this thread.

When talking no-cd patches, you are really using a crack which is illegal and considered reverse engineering. If the game companies allowed you to do whatever you wanted with the game, then why bother with the protection scheme? Also, most user agreements do not allow for use on more than one machine unless you bought licenses to cover all the machines.

I will quote from the end user license agreement found on Blizzard's web site http://www.scindex.com/articles.php?id=40 :

[quote]B. The Program is licensed to you as a single product. Its
component parts may not be separated for use on more than one
computer.[quote]

(ii) exploit the Program or any of its parts for any
commercial purpose including, but not limited to, use at a
cyber café, computer gaming center or any other location-
based site. Blizzard may offer a separate Site License
Agreement to permit you to make the Program available for
commercial use; contact Blizzard for details;
So that negates your use on the LAN argument. And the no-cd crack falls under this as well. If you use a no-cd crack, you are allowing more than one instance of that program to be used on more than one computer and modifying the game...