Well, that's quite different from my experience (it fired once and demanded I phone a number where a licensing goon tried to extract the cost of an entire Windows license from me despite my giving them a key: 'that key is no longer valid because WGA has fired', wtf?).
I suspect that WGA's behaviour (always ill-documented) has shifted over time, and that as soon as you hit humans on phone lines you become vulnerable to the varying behaviour of those humans. I suspect all the variability can be explained away that way.
Still, give me free software any day. No irritating license enforcer and hackability both.