There's not enough info to form an intelligent opinion about Dell's actions or those of the fired employees (if that is in fact the case).
In general, I am in favor of people not having to leave their religion at the door in the workplace. People - Christians, Jews, Muslims - who want to gather to pray during their lunch hour should be allowed to. That doesn't mean that they should get extra paid time for this activity, or that the employer has to provide a dedicated space. But, if people are willing to meet in an empty conference room when they would normally be chatting it up in the lunch room, what's the harm? It's certainly within the spirit of free exercise of religion that is part of our nation's values.
That's fine, unfortunately, Christians don't seem to be allowed to gather to pray together at any/most places of work or education (though I remember reading that there is at least one prayer and/or Bible group in the WH).
If the Muslims get to do this w pay, then us Catholics and other Christians who have special services (I'm unfortunately not very well informed/read on these) get Good Friday and, perhaps, other days of Holy Obligation off or paid time off to attend services. And Jews should get there days of remembrance off w pay. As a side note - 1 of my friends works at the Corp offices of Costco and they've had Good Friday off for years.