Why does my IP keep changing???

Ok, I generally dislike meta-blogging, but perhaps there's a reader out there who knows the answer to my question. As some of you know, I use StatCounter to track visits to my site (Hi Julia). These visits are tracked via your unique IP address (and there's nothing you can do about it).

Rest assured I don't do anything with this information besides count the number of readers I have and pat myself on the back for being so awesome. I don't even know what, if anything, I could do with the information if I wanted to. (It doesn't tell me your name or who you are or anything like that, so chill. It's just a unique IP address and your city/state, that's it. Unless you are the sole occupant of your city/state, you don't have to worry about being identified by me or anyone else.)

I block my own IP from the stats because I visit my site more than anyone, and I don't want it skewing my stats. However, recently this IP kept showing up, and I was all "Who is spending THAT much time on my blog? Seriously?" Well, it's... me. My IP address changed, or I have two, or something. I don't know how this works. Anyway, so I blocked the new IP. And then today...

ME AGAIN! New IP, but still ME. How is this even possible? It's one computer, one internet connection, one XP log-in. I have no idea what's going on, but it's annoying. Any ideas?