How do I check the 'Do not create a new opportunity upon conversion' check-box by default upon lead conversion?

The following solution allows an admin to customize a Salesforce org to automatically select the "Do not create a new opportunity upon conversion" checkbox on the lead conversion screen. This solution uses a Custom Button to REPLACE the standard "Convert" button on the Lead Page Layout.

Please note that this solution does not enable one to extend the same functionality when attempting to Convert a Lead after the using the "Find Duplicates" button, as that Page Layout is not currently customizable.

Custom Button Solution
To do this follow these steps:

• Click on Setup | Customize | Leads | Buttons and Links
• In the "Custom Buttons and Links" section, click on "New Button or Link"
• Assign a Name and Label to the button. It is recommend to have the Name as "CustomConvert" and the Label set to "Convert".
• Choose "Detail Page Button" in the "Display Type" field
• Choose "Display in existing window without sidebar or header" in the "Behavior" field
• Choose "URL" in the "Content Source" field
• In the code section, type the following: /lead/leadconvert.jsp?retURL=%2F{!Lead.Id}&id={!Lead.Id}&nooppti=1
• Remove the standard "Convert" button and add this new button on any Lead Page Layouts in the Detail Buttons Section where you would like this to take effect.

Here list of parameters you can use in the custom button:
Convert Lead

• "Do not create a new opportunity upon conversion" checked -- nooppti=1
• "Send Email to Owner" checked -- sem=1
• "Opportunity Name" -- noopptt={!Lead.Name} - opty
• "Converted Status" -- cstatus=New Status

Task Information

• "Subject" -- tsk5_fu=Mission Critical Task
• "Status" -- tsk12_fu=Deferred
• "Priority" -- tsk13_fu=High

Description Information

• "Send Notification Email" -- email_followup=0
• "Comments" -- tsk6_fu=No Comment

Reminder

• "Reminder" -- IsReminderSet_fu=0