Do you mean the WoW setup (i.e., sound/video settings, macros, savedvariables from addons, etc)? If so, such settings are kept in the \WTF directory and can be account/character specific (depending on the addon if that's what you're asking about). Character specific are stored under \WTF\account\<accountname>\<charactername>

Also, with 4GB of RAM are you running Windows 32bit or 64bit?