Actually you can set up the DNS to point to a 10.x.x.x network. The only people that can view it are the people in your school. With XP you can only have 10 people at one time viewing the site. There is no way to have people outside your network view this unless you can talk your admin into giving you a real ip on the firewall and redirecting it or just port 80 to your ip.
There is a good chance that your ip will change so you may have to update your ip sometimes. Do a search for dynamic dns for some information to automate that.
[10.6.10.170...] will work but only the people at your school can see it. Go to one of your neighbors and type that in and see if it works. If it does not there is nothing you can do.