A client of mine just emailed me about setting up email on her laptop as well as her desktop, so I told her about IMAP.
You can setup a mail client (Outlook Express, Thunderbird, Mail) just like you have it on your desktop. To keep the two "synched", you just have to make sure you are using IMAP instead of POP3. This will keep all your mail on the server, and you can keep a copy on your laptop and desktop by selecting "download a copy to my computer" or something along those lines.
Its too bad GMail doesn't have IMAP yet - they only support POP3 - even for the paid service. :-(
I followed up with this:
IMAP is the right protocol to have automatically synchronized mail.
There should be a setting in your email programs to check every so often, you might want to make both of them a low number to make sure you are getting your email as soon as it comes in. IMAP should automatically get it immediately, but Microsoft may have veered away from the specification as they sometimes do.