One PC at a time.
Here's my way - Turn the paradigm on its head.

When my son sits down to play Ben 10 or Bob the Builder games on the web, he knows he has to click on the FireFox icon to go on the internet. Which is the only icon on his desktop.

He doesn't even know IE exists.

I tell my Wife not to use IE because its not secure. Any time I have to reinstall a windows machine I install the latest FireFox then remove all IE icons from the desktop and start menus.

I had my son's cord blood banked 4 years ago. I recently had a daughter but we didn't save hers.

The reasons i DID do my sone were thus:
1 - We had some spare cash to cover the up front costs and the yearly maintenance is only $75 so its nothing really.
2 - The technology has not been proven but i want to help push it forward because any progress we can make in this area is invaluable. So im not counting on ever being able to use it, just the fact that it MIGHT be possible someday.

The reason we didn't do my daughters are:
1 - The tech is still unproven, we had done my son's as kind of an experiment and we didn't think it was worth it the second time around because of the up front costs.
2 - There is a chance that if anything comes from the tech that my sons cells could be used with my daughter.

Basically I wanted to contribute *something* to try and make this a successful technology but we didnt want to go all in because there is significant risk.

Hope this helps, probably not because we went different ways each time, but i hope you can see my point.