What files should be excluded from a complete Windows backup?
Solution 1:
CrashPlan isn't really meant for the type of full-system backup you're describing. It's meant for backing up your data. Even if you were to come up with some sort of master list of non-ephemeral Windows files and back everything up completely, you still wouldn't actually be able to restore it on a fresh installation because Windows wouldn't allow you to replace system files and all the other files that are in use while Windows is running. It's also not going to play very well with the various DRM schemes that applications/games use.
If you really want a full-system backup like you're describing, you're going to need to use another product based on disk images that supports bare-metal restore.
Don't get me wrong. I love CrashPlan and use it for all the computers in our house. But you have to use it for what it was intended for which is preventing you from losing data, not applications and system configuration. If you have specific applications that you really don't want to have to re-configure on a fresh install, analyze them individually and figure out where their configuration settings are stored. Then back those files up explicitly. If you're lazy, backing up the AppData folder in your user profile will get you 99% of the way there.