I haven't checked my ISP mail inbox for about six months, but that doesn't mean I'm out of touch. I get the messages delivered to my Gmail account automatically, which allows me to read the mail on any PC with an Internet connection. I can even reply or send new messages in Gmail as if they came from the address my ISP supplied.
Start by logging into your Gmail account, or if you don't already have one, sign up here. Click Settings in the top-right corner of your inbox, and then choose Accounts. To receive mail addressed to your ISP account in your Gmail inbox, your ISP must use POP3. If it uses IMAP, you can centralize things by forwarding your Gmail messages to your ISP-supplied address. I'll describe how to configure this on Monday.
Select Add another mail account next to "Get mail from other accounts," enter your ISP mail address, and click Next Step. Enter the ISP account's user name and password, and the POP server address and port. The server address will likely be pop.your ISP's URL; check with your ISP if it's otherwise. If your PC uses Windows and you're using SSL to connect (which I recommend), the port will be 995 (110 if you aren't using SSL).
Chances are you'll want to access your mail from any PC, so check Leave a copy of retrieved message on the server. I also suggest using SSL (I'm repeating myself), and label the messages with your ISP account's address, which makes it easy to tell at a glance where the message was originally sent. Click Add Account, check Yes, I want to be able to send mail as (that address), and click Next Step. You can change the name of the sender, and specify a different reply-to address, if you wish.
When you're done, click Next Step again. Now select Send Verification, open your regular mail client, click the confirmation link in the "Gmail Verification" message, or copy the verification code and paste it into the Verify field back in Gmail. Finally, click Verify.
Monday: Turn things around by getting your Gmail messages delivered to your ISP account's inbox.