how to change DNS settings network manager over writes every thing

[Abhishek Dixit]

I am facing problem in using my internet so as per recommendations here
http://www.indiabroadband.net/broadband-how/29007-how-get-max-speed-connection.html
I have to change my DNS settings to
Open DNS
Preferred DNS Server: 208.67.222.222
Alternate DNS Server: 208.67.220.220
or Google DNS
Preferred DNS Server: 8.8.8.8
Alternate DNS Server: 8.8.4.4

here comes my problem,I went to wifi signal icon at top right hand
cornet adjacent to volume icon in tool bar upon clicking
edit connections-->wireless-->my connection
all the options with respect to settings were greyed out.So I could
not do it in GUI.
I decided to write the settings in /etc/resolv.con
but when I did /etc/init.d/network-manager restart
all the DNS settings were wiped out.

Given the situation what are my options?
-- 
Regards
Abhi