Look into IMAP. It's an alternative to POP that stores all your mail on your email host's server, instead of on your hard drive. That way, no matter what computer you're accessing it from, it's always looking at the EXACT same email.
Most email hosts allow an account to be set up as IMAP.
And setting it up on your computer takes a few more steps than POP email, but tutorials abound on google, or I'm sure the people here could give you some pointers if you run into problems.
Good luck!