Yes, as long as you are using something added to your minecraft that does not give you any advantage over other players, then it is alright. Better that you asked though to make sure it was alright than risk the chance of it being not.

Yea, what Lickster said, basically anything but X-Ray Texture packs.

Thats exactly right, thanks for posting this topic too cyerye, I looked at the texture pack and now use it myself.