i have found some armour called cornugan hide armour, and it says it has a damage reduction of 10/+2 what does this mean? i'm guessing it gives a reduction of 10 points in damage for weapons that are of +2 enchantment and below, am i right or am i compleatly wrong?

Close.

10/+2 Means that you get 10 points of damage reduction, UNLESS struck with a +2 weapon. The +2 weapon overcomes the damage reduction.

is this armour any good then? i'm currently at the fell wood. so will it be of much use against the baddies in that area and beyond? or would it be better to stick with chain mail, that i have already. the armour class will become 2 pts lower. will the damage reduction over come this?

If your question is whether a 10 damage reduction is better than 2 points in AC, then the answer is definately yes. I'd take damage reduction anytime... but... I think the main question is how many enemies use +2 weapons and better, if many enemies do it, the armor is rather useless.
I hope someone here can give you more info on this.

thanks that makes sense. is there much problem from +2 weapons around the fell wood area?