Hi
The different cores on any multi core CPU will run at different tempertures and there is little that you can do to stop this happening. However it is not normally more than a few degrees and won't be detrimental to the running of the system.
I do know what you are referring to about the default location of the instal box when a program is being installed in XP. To be honest I can't remember the exact registry hack now for it but it might not even work in Windows 7 anyway and it is no biggie to just makle sure that you change location to the D drive or anywhere else you want to use as the default drive for program installation.
