This should explain my position a little more clearly, and I wish I had said it this way in the first place to avoid confusion.
I believe that in Purgatory the souls suffer at least two types of punishment. One is the fire, or purification. The other is the loss of the Beatific Vision, or being seperated from God. It's been written (though I don't know how it would be known) that the second is worse than the first.
After the purification, the seperation still remains as part of the suffering. It is in this state, I believe, that our prayers can effect the length of stay of those in Purgatory.
It is while in this state that our Blessed Virgin can appeal to Her Son for our release, as she promised.
It is in this state of untold suffering that protestants languish because of their lack of belief, and because they have nobody to pray for them. They may remain there till the end of time, that's how powerful prayer is.
Here is a portion of the Catholic doctrine, including a few thoughts on the subject by Aquinas.
http://www.newadvent.org/cathen/12575a.htm
I don't think it contains exactly my position, but only portions of it, which would help it make more sense, as well as explain the promises of Our Lady, through the Immaculate Heart, and the Sacred Heart of Jesus.
Are you assuming the protestants got there through invincible ignorance? Because their religion sure didn't help any.