Block websites without any software
1] Browse C:\WINDOWS\system32\drivers\etc
2] Find the file named "HOSTS"
3] Open it in notepad
4] Under "127.0.0.1 localhost" Add 127.0.0.2 www.orkut.com , and that site will no longer be accessable.
www.orkut.com is now unaccessable
For every site after that you want to add, just add "1" to the last number in the internal ip (127.0.0.2) and then the addy like before.
This also works with banner sites, just find the host name of the server with the banners and do the same thing with that addy.
Hope this small tutorial could keep you going in simple way of blocking websites..