I got an email the other day from DriveThruRPG.com about Teach Your Kids to Game Week. I'm not sure if it's this week or next or whatever, but I figured I'd share my most recent experience. I've written about this before, as I was teaching my three oldest the ins and outs of Type IV D&D. We made it through a few sessions, enough to level them up to 2, before the chaos of having a large family intervened. I have since become enamored of the newest edition of Microlite, and decided to convert the kids game to that system.
They didn't want to lose all their stuff, or make new characters, so I had them roll stats (4d6 drop the lowest) and did the rest of the chargen myself for them. All in all, using Microsoft Word, I was able to put all their characters together in as much time as it took me to do their Type IV characters in WotC's online Character Builder. I was also able to create a new character for the youngest boy (age 6) so he wouldn't be left out of the fun. It was a piece of cake to modify the magic items they already had from 4E to work in the Microlite74 system.
All in all, we managed to play for about two hours. A lot of that was spent with the kids joking around about everything. I am running them through the old 4E adventure "Keep on the Shadowfell", which is a straightforward enough adventure and features a large, rather old-school type of dungeon to explore (old-school enough that it is pretty much a total failure as a Type IV D&D module!). They haven't gotten to the Keep yet, but they will soon enough.
I'm not sure if I really have any good advice for gaming with kids, though. Try to do as much of the chargen yourself as is possible. Use a simple system; the 4E power cards can induce a rather debilitating type of analysis paralysis in certain kids, and combat can really drag in that system. Kids are naturally old-school gamers, believe it or not. They want to try anything, and they need that kind of freedom. The "yes, but..." DMing style is absolutely crucial in this type of game. Encourage them to be descriptive, and they will go all-out. At least, mine did, but they are always trying to one-up each other.
Gaming with kids can be very rewarding. I know I had a blast playing with them, and I know they all enjoyed themselves (even when it seemed they weren't; nobody likes to miss their attack roll!). So, if you have kids, game excellently with them!