Ditto on the Milwaukee tools, they make good stuff. I've used the little Makita drivers, they work awesome, very small and light, and plenty powerful. As for half-inch, buddy at work had an Ingersoll-Rand for the longest time until the battery pooched out (frikken Ni-Cad's).
ALWAYS get something with Lithium-Ion batteries. Why ? 2 reasons. One, they last forever on a charge and are as strong near the end of their charge as they are at the start. And two, they don't have a charge memory. Meaning whether it's full or half full or 3/4 or empty, when it charges it doesn't develop a "memory" like NiCads can. They don't always charge full once you've charged it from 1/2 or 3/4 charge, and after a few times they won't ever get full charge. Ni-Cads you gotta run them dead every time before charging to get the best and longest life outta them.
We have a 12v Snap-On that's good for about 10 minutes of fooling around, then gets dead quick. Charge it, and in 15 minutes it think it's full, but it isn't.