That's a great theory, Alien3.
I'll point out the obvious and say that it has to be the royal facehugger that gets Ripley, but the way I imagine it, both of them approached the cryo tubes. The royal hugger went for Ripley, and the regular one for Newt. Somehow the royal hugger successfully got to Ripley, but the regular one cut itself on Newt's tube, starting the fire and ejecting everyone down to Fury.
After this, all it had to do was survive long enough to meet Spike.
This is one of the best explanations I've read yet. I really rike it. Nerd level 9 to you sir.