I use Hotmail Live and my emails are forwarded to my Blackberry without any extra cost. I set it up using the Blackberry itself, without going anywhere near Hotmail. All I had to do was input my Hotmail address (I think it was under email settings) and it took care of the rest.
Works a treat with one small point, I have emails from a particular Yahoo list diverted to a separate folder and I can't see emails in subsidiary folders. I assume you can if you set it up through Hotmail itself?
I'm far from an expert on this stuff, but it's handy to be able to view my Hotmail mails without a PC.