Stop spam from Joomla contact form: Anti-spam by Captcha for Joomla 1.5

After installing a contact form in Joomla 1.5, I recieved lots of spams through "Contact form" in Joomla into my email.
Here I want to share my efforts for finding one of the best solutions for solving this problem.
Officially, I appreciate so much owner of this patch for Joomla at: http://www.latenight-coding.com/

All information can be found on this webpage:

http://www.latenight-coding.com/joomla-addons/qcontacts/documentation.html

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My Descriptions:

QContacts is a contact manager component derived from com_contact the standard component distributed with any Joomla! installation.

QContacts offers the following additional features
* More contact fields: Skype Id and Yahoo Messenger Id.
* Up to 6 custom fields can be added to the online contact form. 
* An optional captcha verification image can be displayed to prevent automated programs (spambots) from sending spam email messages through the contact form.

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Procedure:

1) Download this ZIP file
2) Install this ZIP file into your Joomla Admin panel Extentions-> Install
3) Go to Components-> Qcontacts and define a new contact. Also for this contact, you can go to EMail Parameters and set "Captcha" as "Yes" with the length of 5 or 6 
4) Go to Menus-> Main Menu and define a new QContact Menu
5) That is all...