At what age did you allow your children to play games on the computer and/or video games of any kind (educational or not)?

Very simple question, wrestling with whether or not to get my almost 5 year old (he turns 5 next Thursday, shudder!) started on some Leapster TV learning stuff and/or computer kindergarten learning games…as, generally, I’m not a huge fan of having any of my kids plugged into anything with screens for any purpose…Just let me know what age and reasoning behind your decision. Thanks!