Hmmm, All the things I would've recommended seem to have been said already, ---- lol! If your son is interested in sports, Vip gameszone might be good, as they have some relatively easy to play sports titles, ---- which can also be played online against another person. wellif your son isn't familiar with audio games, depending upon his general auditory coordination, you might think about starting with some of the more 2D games, such as Superliam, judgement day, Alien outback and the games from www.bscgames.com, rather than leaping streight into somethin like Monkey business, tank commander or Sarah from http://www.pcsgames.net/
Sinse being 3D, they require more memory, more hand/ear coordination and might be a bit much at the start. appologies if this sounds slightly pessimistic or unfair, I'm just remembering articals I've read about mainstream graphical games now being incredibly complex, ---- and I will admit it took me a while to get to grips with Shades of doom etc.
All the games accept Monkey business have free demos though, so there is always the chance to try them out first.
Pcs games does however provide a great list of all accessible games, which it might be handy to look at as well.
Also, you mention your son is learning Jaws? Jayde mentioned online games, and perhaps this might be a funthing for him to practice Jaws on.
some things that are easy to play, but highly fun are online gamebooks. These are fantasy stories, sometimes involving a basic combat system where you progress through the stories by clicking links to say where your character goes next and what he/she does. on http://www.whitestick.co.uk/fantasy.html there is a list of various gamebooks which might be good to try, in particular the lone wolf gamebooks from the project aon site at http://www.projectaon.org/new.htm
but please be aware that several others on that list are not family friendly, so you might want to check out the individual books first ( the Lone wolf stuff on project.aon are all perfectly okay though).
Also, there are some streight online text rpg and stratogy games which require subscriptions. I'm personally a huge fan of Sryth found at www.sryth.com , a massive fantasy rpg in the style of the gamebooks I mentioned earlier but with many more pages, but there are quite a few others. Some may be a litle too complex in the statistics for your son, but there are deffinately others it'd probably be worth looking at.
You can find a list of screen reader accessible online games at http://www.whitestick.co.uk/ongames.html
I hope some of this is vaguely useful.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)