It's a terrible idea to keep your anger bottled up inside. I used to have a lot of temper problems as well (and still do on occasion, but not as much).
You have to let your anger out somehow, and I've found that talking to myself (however psycho it makes me look) works very well. In particular, cussing like a truckdriver to myself works even better. I'm not sure why talking to myself helps the anger slowly dissipate, but I think it's more of a listening thing. After all, there's only so much you can tell someone else before they stop listening. However, you're always listening to yourself, so in a sense, you are your own best listener.
Playing an instrument also helps greatly with anger. I personally am a piano player, and when I'm pissed off to the max, I start playing whatever comes to mind on my piano.
As for wanting to kill someone in the midst of a heated argument, I think that's natural (not that you'd actually kill someone). When the heart starts beating super-fast during an argument, it's only natural that your adrenaline would go up quite a bit. Honestly, heated arguments are often unnecessary. Once one person starts yelling and saying totally irrational things, the argument is basically over, since that person is most likely not going to give up their position, no matter what the other person says.