Some older games do NOT like dual core so manually setting the affinity fixes it....there used to be a windows app called set affinity that would look for and auto set affinity, but it seems to be gone.
The dual core optimizer is intended to fix compatability issues with some older games that may experience some stuttering or slowdowns with an AMD dual core processor. It is for XP.
Vista does not need the patch. I don't think it will even install on Vista.