just modify the hosts file located in c:\windows\system32\drivers\etc\hosts (assuming you are using xp, if not just find out where the file is in your operating system)
right click, select "open with" , select 'notepad'
add an entry at the end (well anywhere it works but to keep it organized add it at the end of the file)
127.0.0.1 www.websiteiwanttoblock.com
save the file and then check with the browser that it was blocked , voila
(of course someone with tech knowledge can undo this but assuming your users are not very savvy....)
right click, select "open with" , select 'notepad'
add an entry at the end (well anywhere it works but to keep it organized add it at the end of the file)
127.0.0.1 www.websiteiwanttoblock.com
save the file and then check with the browser that it was blocked , voila
(of course someone with tech knowledge can undo this but assuming your users are not very savvy....)
