I am new to the forums, so greetings to you all...
I have a similar situation, and an interesting project to go with it. I am looking for a distro for older hardware as well, ranging from really old (A 386) to 2-3 year old machines with 1 gig ram or less. I am working on collecting old computer equipment from people in my area, to re-purpose this "obsolete" equipment to give to families with children who don't have a computer. as long as they can use the machine for word processing and researching online they should suit the purpose.
Right now on the newer equipment, I am trying out edubuntu, but I am wanting to check out other options to find the one best suited for this project. Eventually I would like top be able to offer 4 different age appropriate options, I.E. one install for prek-6th grade, with very minimal or no internet use, one for 7-8 with parental controls and internet privacy focus, one for 9-12 with full internet capability but still with privacy in mind, and finally, a full function machine for college students, this one will probably use just straight ubuntu or kubuntu, as they are the easiest I have found for new linux users, but I am open for trying anything. My goal with this project is to eventually start a non profit to distribute these computers on a larger scale. for now, I have 6 kids as my testers I would like to have machines for by Christmas.
I am also interested in suggestions for educational software for each age group as well, but that is a separate issue. for now, I need a distro suitable for older equipment. I am most familier with Ubuntu and Kubuntu, but a quick learner and willing to try out anything. The only other requirement is a distro that is good to go if the computer is not able to connect to the internet.