My soon to be 7 year old nephew, *loves* Kinect Adventures, and Lego Harry Potter (But the first Harry Potter movie was a little to scary for him.)  I didn't have Kinectimals to show him or I think he would have gone insane for it.  And Peggle, he did really well, and really enoyed Peggle.

He also liked Pac-Man CE DX demo - he played it all the way to the end (of the Demo).   Too bad they don't make a 'Diego Rescue' game like they do for the Wii - those are good kids games.

Plus show him how to set the menu to 'kids/family' settings (a recent Xbox 101) so that they will see more apropriate games and movies the Dashboard.  Netflix is another great bonus you get with any of the systems now.

ZappyKins

Tell him to get his son an original Xbox instead, and this as his first game:

http://uk.gamespot.com/xbox/puzzle/thebiblegame/index.html

That's if you like the pastor. If not, recommend Dante's Inferno or something.

I have a 5 year old son who loves to game.  Here is the list of games he plays and plays well.

Uno.

Lego games.

Teenage Mutant Ninja Turtles (1989 remake and the HD one, shell in time or whatever)

He's dabbled in some other arcade titles, but he's not quite there for hand-eye co-ordination.  With practice though he could probably play some more advanced games.

Come on people, don't let him grow up to be a casual! To OP- get some of the games I mentioned like Tales, Banjo Kazooie and Lost Odyssey. Set him on the right path from the start. 

Also, as an aside, the more you shelter a kid the more they are going to experiment. By getting him kinect you ensure he'll be a loser with a drug addiction in his future. If you get him tales or LO he will grow up to be a congressman with a drug addiction. 

Have you ever met a 5 year old?  LO, good lord.  Most adults don't have the patience to sit through that (although I loved it), never mind a 5 year old.

When I was five I played those types of games

Sonic SEGA All-Stars Racing, Banjo & Kazooie Nuts and Bolts, Viva Pinata Party Animals and just Viva Pinata. Hmmm what else...?

The Lego series would be good for them.

I'm sure there's more but those would be great for them :) Hope that helps.

How do you even remember what you played when you were 2 lol.

Being 4 is the earliest I can remember anything from.

You're right, I think I was either 4 or 5.. But nonetheless, it is possible to remember things that far back, as long as they are significant enough. I remember being in the shallow pool with my dad and he told me he wouldn't let me drown :-/ Now I'm 6,1... I don't think it's possible for me to drown at the shallow end if I layed on my back, lol.

My neice and nephew (8 & 10) love XBLA, lots of easy to play but engaging games for them.