Greeny, many fansub groups use IRC channels, which allow you to download files in a non-P2P manner using xdcc. For Mac OS X, I recommend
Colloquy (just make sure in the "Interface" tab of the preferences to check the box that says "Show Notices as Private Chat," or the way Growl makes them disappear will annoy you to no end). Usually it's best to find out what groups are subbing the anime you want to watch and go to their website to see what they're releasing - almost every single fansub group I know of releases both a "low quality" and "high quality" version because of the CPU requirements of high-resolution H264 decoding. You can usually find the name/location of their IRC channel in there somewhere too.
Also, on the subject of torrents - with a proper torrent program, you can limit your upload speed to be as low as you need for your ISP to be okay with the outgoing traffic. On Mac OS X, I recommend
Transmission above all others. It's lightweight, open source and has an incredibly good GUI.