The argument from motion usually takes on something like the following form:
1. Evident to the senses is motion. (Premise)
2. Everything in motion has its motion sustained by another. (Premise)
3. Either an Unmoved Mover exists, or else there is an infinite regress of sustaining movers. (Implied by 1 and 2)
4. There cannot be an infinite regress of sustaining movers. (Premise)
5. Therefore, an Unmoved Mover exists. (From 3 and 4)
I believe this argument is sound. Suppose, however, that one is convinced that Newtonian, Einsteinian or quantum physics somehow undermines premise (2). Notice I'm not agreeing, and I think such an objection is based on a misinterpretation of both contemporary physics and Aristotelian metaphysics. Nevertheless, even if the objection were a good one, the argument can easily accommodate this point.
(2) can become (2*): There is a regress of things in motion that requires its motion to be moved by another.
If this is correct, then the existence of an Unmoved Mover may still be deduced. For example, an acorn's potentiality to become an oak tree cannot actualize itself. Rather, its motion is causally dependent on the sustaining power of the acorn's environment, e.g. soil, water and sunlight. Hence, if the regress of sustaining movers cannot be infinite in this instance, then the conclusion that an Unmoved Mover exists remains a sound one.