For God's sake, saurav, can't you post your answer in a single post?
Yahoo doesn't have a free POP3 server, you have to register for their premium service.
Hotmail should be configured as a HTTP server in Outlook Express and Microsoft Outlook, not as POP3.
For Gmail, run the autoconfig tool by downloading it from here and following the instructions.
*toolbar.google.com/gmail-helper/GmailConfig.exe
Or visit this page for step by step instructions along with screenshots.
*gmail.google.com/support/bin/answer.py?answer=13276