POP3 E-mail in Gmail
From Lunarpages Web Hosting Wiki
For those of you who have your own POP3 e-mail account that came with your web hosting for your web site - would you like to import that mail into Gmail? Using Gmail's Mail Fetcher, you can download messages from up to five other email accounts, centralizing all your e-mail in Gmail.
First thing you must do is login to the Gmail web site, and then click Settings at the top of any Gmail page, and open the Accounts tab.
Now on the Account web page, scroll down to the Get mail from other accounts section, click Add another mail account. Now Gmail will walk you though a wizard (like with any other e-mail client) to gather information about your e-mail account.
Now personally, I would make sure you check not to keep your messages on the server. This way all your messages are sent to Gmail and stored there, and you don't have to worry about cleaning out your server side mail from time to time.
Once you have finished with the wizard, hit click Add Account. Now you can use your e-mail from your web hosting account with Gmail. If you are a fan of Gmail, this will keep you from having to jump from client to client to get your e-mail all checked.
For more help, check this link: