Then again, it won't really matter, as you won't spend much time staring at your dead body anyway. Instead, CoD4 immediately cuts to a Kill Cam view when you're shot down, enabling you to see through your killer's eyes during your last few seconds of life. This isn't just macabre or humiliating; it'll also give you a chance to see where you went wrong, something that helped our performance immensely.
The upgrades you'll earn are all driven by experience points, which you'll earn mainly through kills. In regular, free-for-all deathmatch, a kill is worth five points, while in team deathmatch it's worth 10. (Killing silently with a knife doesn't seem to earn you any extra points, but it sure is fun if you can pull it off.) Assisting a teammate in taking down an opponent, meanwhile, nets you a measly two points - which is still a hell of a lot better than watching your buddy take all the credit.
Assuming you can stay alive while racking up kills, you'll eventually earn cool rewards that'll give you an even bigger edge. Three consecutive kills nets you a slow-scanning radar that gives away enemy positions (although there's a Perk that'll let you avoid being detected like this), while five lets you call in an earth-shattering airstrike on an enemy position. Seven kills, meanwhile, will enable you to call up a helicopter gunship that floats lazily around the map, disemboweling any opponent dumb enough to wander outdoors.