It's just on downloads under graphics->processor graphics->2nd generation... Select windows 7 64-bit and.. and...
It's not there anymore.
It just downloaded this a few days ago and it's not there anymore. Maybe they pulled another new update. I have 184.108.40.20622 (220.127.116.11.2622) released on January 20th that I only downloaded 2 days ago but it's gone now.
It's still available if you search for Intel for 18.104.22.16822 but I don't see any explanation for it being withdrawn so you might not want it.
I think perhaps Flash and Silverlight might stutter a little less when streaming video with hardware acceleration enabled. I don't really use my mini for gaming, just media, work, etc. I haven't noticed any big changes. I run with an i5-2305S (65W) cpu at 2560x1600 on a displayport.