Once you get a heart monitor you'll be even more obsessed - like the rest of us!
Go to the polar website, I think it's polarusa.com They have a lot of information about why you want a heart rate monitor. You can also compare the most basic thing to the one with all the bells and whistles. Once you know what your options are, then you can choose what features you want.
I bought mine on ebay very cheap and I'm very happy. I hear that voids the warranty though.
Welocme aboard