For me, I think it
is important to take physics 1 before taking the OAT. I feel that physics is a subject that you really have to understand the concept and apply it to a problem, you have to be clear minded and be able to think relatively quickly. I feel that it is different from chemistry where you see 2 or 3 mole problems, you have seen it all. For physics, they can change one tiny part of the problem, and the calculations part will be different. Like for 2 D projectile motion, incline problem, there's so many ways they can ask it. One key trick in physics is to think about sum of the forces, for every problem, which can be vastly different for diff types of problems, so it really requires you to think clearly. And OAT is known for putting a common wrong answer among the ans choices, so you really gotta know it, plus theres the time constraint too.
If you can't take physics 1 by the time you take the OAT, I suggest you get your hands on either Princeton MCAT physics review, or the Kaplan big book OAT book + the physics subject tests. I think those were VERY helpful in preparing me (got 370 on this section), since they are harder, so it really drills in the concepts.
you might also want to check out this thread, its about taking physics and the OAT
http://forums.studentdoctor.net/showthread.php?t=467063