Which Modern Warfare 2 Killstreak Rewards count towards your current kill streak?

Solution 1:

As far as I know, Pavelow has always counted. Only care package drops/sentry guns don't count and any killstreaks that you earned in a previous life do not count. All other killstreaks count towards a higher killstreak as long as you don't die.

That is, if I were to earn Pavelow via a 9 kill streak and then die, the kills that the Pavelow will get will not count towards a nuke or EMP.

Solution 2:

There used to be a glitch surrounding the Pave Low. Before, only the first Pave Low called out would contribute to you kill streak (and then only sometimes). I believe this behavior was patched and it acts like a normal kill streak now. You are right about care packages and emergency airdrops though. However, I believe if you get a crushing kill by dropping the care package on someone, that does count (not that that happens very often).