The numerous options for taking advantage of homeschool software and using the internet in your homeschool class room will sooner or later raise the question of getting your child their own laptop. While some see this as excessive I see this as moving towards the future. While I was in college laptops in the class room were not common but not unusual, today they are the norm and I fully expect when my kids go to college books will be obsolete, and laptops and e-readers will be the norm and required. This is progress and our job is to prepare our children for the future. Part of that future is exposing them to computers and teaching them how they work, the intricacies, the shortcuts, and how to maximize their usefulness.
I think it is important to start out with a low cost model and lay some serious ground rules. I am not going to go into what I think these rules should be they differ from house to house and child to child. But as a whole they should encourage the student to use the computer for productivity and learning as opposed to being a time drain device of distraction.
Install some software that is applicable to their interests. Walk them through the most basic steps of file saving, show them how to add and remove programs, show them how to get web help, assist them with setting up an email account. Let them know that you trust them to self censor and then watch their internet usage like a hawk.
In the class room require them to learn to take notes on the computer, let them practice their typing. Do a power point presentation on something that excites them, fill their favorites with approved sites that will keep them busy for awhile.
At the end of the day letting your child have a computer is akin to taking them to their first library and turning them loose, just on a bit of a larger scale. Granting them access to their very own computer and the rest of the world through the internet is empowering, see where it goes and recognize new interests that arise because of the new opportunities that confront them.
Proceed cautiously but by all means do not do your children the disservice of keeping them in the dark for too long and shielding them from the truths of the outside world. Use protective software and other homeschool software to maximize the experience.