I had a Hotmail account years before Gmail was around, and I still keep it around just in case I get an important email there. I tried to use Gmail's "Get mail from other accounts" feature, but it always said "connection timed out". I had just assumed Hotmail offered POP3 - it doesn't. I found a helpful article on LifeHacker to get around this issue, but the software they mention is not a free service.
But, buried in the comments is a link to the "GetMail for Hotmail" Windows service. That link, however, sends you to the vendor's Web site, which wants you to sign up for a free trial of some other service in order to download the software. But, this Download.com link will let you download it with no strings attached.
You do have to enter your Hotmail password so that it can retreive the mail, which may be a deal-breaker for some. To be safer, I changed my Hotmail password to make sure it doesn't match any other service I use. I'm also confident that I don't use this account for any service I use, though that still doesn't technically make me 100% protected. I'm also keeping an eye on it from a network perpective to make sure it's not trying to do anything it's not supposed to. I may actually attempt to write my own simple version of this some day just for the extra piece of mind. The program also is a resource hog, so you don't want have it set to fetch mail too often.
It does work well, otherwise, though. I've got mail set up to go directly to my Gmail archive (Settings --> Filters), and labeled with "Hotmail", so it's separate from my regular Gmail mail. I also set up my Hotmail.com account under "Settings --> Send mail as" so that I can have email sent as if it came from Hotmail.
If everything keeps working well, I'll be very glad to not have to log into Hotmail anymore.