You seem a little confused about all this. You said you wanted to Archive & Install 10.6 to get a "mostly clean copy" of the system. That's exactly what just running the Snow Leopard installer again will do. An Archive & Install option would do that too, but (assuming it worked like the old one) it would also create a "Previous Systems" folder, move the old system to it, & deactivate it. There is no way to reactivate this archived previous system once deactivated, if that is what you were thinking -- it is just a way to preserve items that you might need to add back to the newly installed one later on, like third party extensions or a user folder if you opted not to preserve users during the A&I.
Note that you do not need to erase anything first unless you want to clean out everything, including user preferences, system settings, & anything else that might be causing the problem. This would be true even if an Archive & Install option was provided, since it doesn't clean out those things either.