Just to follow up on some of Kamikaze's advice...
A lot of people seem to have fallen into a sort of 'long skis truck, short skis suck' rut, probably in reaction to the ever shortening of skis that was happening a couple of years back. The right ski for you is the one that you find to be most appropriate after a few on snow demos and some good info. You probably don't have the chance to demo on snow, so we'll start with some generalities that I find to be true, and that I use when helping my customers select a ski from the wall.
1- shorter skis turn faster
2- shorter skis are usually a little more unstable at high speeds, BUT this can depend on width
3- the wider a ski is, the 'slower' it goes edge to edge, but then skiing technique and simply getting used to your new skis will change that pretty quickly, as will some rise under your bindings if you're too lazy to deal with the width
4-a longer ski will feel/maybe be faster
5-a longer ski wil usually require more effort to turn
6-Finding a long ski that is really soft is a hard thing to do(no matter what some morons will say about K2s and Salomons)
So, going with some of this, examine your skiing. Where do you ski? If your answer is mostly park, then you can afford to go shorter. If your answer is only big mountain style lines, whether out of bounds, or even inbounds at places like Whistler-Blackcomb, go longer. If your answer is 'a little bit of both', you can probably go medium length. If your answer is 'I'm a complete fuckbag who doesn't know ass from dick and can't ski worth shit', go shorter.
Now, if, like most kids I deal with, your answer is 'I ride about 33% park, 33% 'bigish mtn lines', and 33% fucking around with my friends anywhere on the mountain, including some groomed once in a while', then it gets easy. Taking into account your height, weight, etc, I'd probably slot you into a something between 175-185, mid-fat. 80-86 mm at the waist, though you could go up to 90-95 depending where you are. Keep in mind that I ski Whistler almost exclusively, so 'midfat' to me is 'pretty damn fat' to most people.
Having gone through all that, I know damn well what you're going to do. You're going to pick your skis based on the graphics. I think Line, Armada, Volkl, K2, and 4Frnt have pretty cool graphics, so you could just randomly pick a midfat twintip in the 170-180 size range, and you'll be ok.
Next time, try your local shop. Sure, it's probably filled with idiot students making $5.50 an hour plus commission, but it's still better than the internet.
'No i dont care about your post count, i care about you being a cocksucker.'
'My friend's and I formed a NO GIRLS ALLOWED club when we were little. Then we gave it up when girls made my penis get hard'
'I think skiing in general is just a phase'-My friend Josh.