Simply put is there a conditional command that will have a macro look at my targets life as to change what it will do based on the current life percentage of my current target.

I.E. if target over 50% life use <spell 1>
    If target at 50% life or less Use <spell 2>

No, I'm 99.99% positive there is no way to check what amount of health the target has.

To do that, you'd have to click on them, but if you are saying that the macro decides what spell to cast... that's a little advanced for WoW right now, I'm thinking.