AMDZone :: The real #1 source for AMD news, reviews, and info. Est 1998.. Both AMD and Intel as well as nVidia and ATI have been busy.
The latest nVidia drivers post version 80.xx support dual core improvements as do ATI drivers 5.13 and later. The performance improvement isn’t large as most games are graphics bound, but they are there.
Also, Intel has been busy optimizing games for dual core and hyper threading. Both Quake and Call of Duty 2 have patches (1.05b and 1.01 respectively) that improve performance. Unfortunately, it is only about 5% at high resolutions. Also the patches are incompatible with the improvements in the nVidia drivers, so go figure. Either load the latest nVidia drivers and disable dual core support or use nVidia drivers without these specific fixes.
It is a young set of software :_)