How to block a website

[Doctor_hv]

I would like to block access to a specific web site in Firefox and IE7, but I don't want the person to know that I have blocked the access (my friend just can't get off some sites and I can't be rude to tell him to f** off because I have to work) so if I use content blocker he gets the alert...
So, is there any program I could use to block off access to some sites in all programs without the person using them knowing it has been blocked...
Thanks...

 

[DelJo63]

use NSLOOKUP www.whateverdomain.com to get the ip address

add the ip address to the host file located at
\windows\system32\drivers\etc\hosts

and the line should look like

ip address <some spaces> ip address from nslookup​

this needs to be performed on the system your friend is using