Ashley,
I think of P90x without a barbell, kettlebell and a lot of the weighted movements
CrossFit has given me a pretty decent amount of strength. Just last night I did 17 dips unbroken with a 55 lb vest. I was pretty amazed because I had never attempted anything like that. I just kept stacking on weight. I know I can do a lot more (judging by the reps), but the bar began to bend (I weigh about 200 lbs, so add another 55 on a crappy bar and you do the math)
This says a lot for CrossFit and strength acquisition. I could barely do 3 or 4 when I started and never really trained much at dips.
It's not as beneficial for strength as SS, but there are so many other benefits you get in return.
Hindsight, I probably would have started with SS, just to make me a better CrossFitter LOL... well, ok, to increase my power output
