What directories do you backup?

What directories do you use as “Default directories to backup”?
Something generic, like “C:”, with lots of entries in “excluded files” or something very specific, like “C:\Users;C:\Documents and settings;C:\ProgramData;” ?

Do you usually backup C:\Windows\ or C:\Program Files\ ?
I don’t think those are needed in file-level backup, because they rarely change (and you can still recover them from image backups). What do you think?

I use

Default directories to backup:
C:\Dokumente und Einstellungen;

Excluded files (with wildcards):
C:\Dokumente und Einstellungen:\Lokale Einstellungen\Temp;
C:\Dokumente und Einstellungen:\Lokale Einstellungen\Temporary Internet Files;
C:\Dokumente und Einstellungen:\AppData\Local\Google\Chrome\User Data\Default\Cache;
C:\Dokumente und Einstellungen:\AppData\Roaming\Thunderbird\Profiles\697f7osg.default\ImapMail;

Note: Dokumente und Einstellungen is the users directory in german language.