Jacobamf, here is what you need to know:
there are basically 3 types of twin-tip skis:
All-mountain: stiffer flex, thinner waist, bigger side cut, good performance all over the mountain. Some example are the Line Chronic, K2 Public Enemy, Ninthward First Blood, Dynastar Trouble Maker
Park: softer flex, fatter waist, bindings mounted closer to the center. These slide rails better and spin better because they are mounted in the middle, but the softer flex means when you take them outside the park they won't edge as well. Some examples are Line Invader/Anthem, K2 Fujative, Ninthward Butterliscious, Fischer Addict, Dynastar Nothin But Trouble
Powder: longer skis with fat waists and smaller side cuts. These will perform best in powder and in the backcountry, but on groomed runs they will feel too wide to turn well. Examples are Line Elizabeth, Rossi Scratch BC, K2 Seth, Dynastar Big Trouble, Ninthward 187, Armada JPvsJulian
So you basically need to think about where you will ski more. If you are learning and need skis that are well rounded, I suggest all-mountain skis. Also, if you live in the east coast where there is less powder, powder skis won't be a good choice. If you live in the west and love backcountry, go with a powder ski.
The other thing you need to think about is the core of the ski. All the ones I listed are wood cores (if i recall correctly) which will last a long time. The Salomon 1080 series are all foam cores. While foam is lighter and performs well, tiny cracks form in it every time it flexes and it will gradually get softer. You can only use foam cores for about 1 season.
So, for yor first pair, I reccomend you avoid Salomon because they are expensive and won't last. Also, Armada are very expensive although people seem to like them a lot. I reccomend Line skis for your first pair though, because they will last a long time and the price is better than the others. Go to all the ski companys' websites though, and look at the specs and reccomendations they make. Then go to
www.getboards.com to find out the real prices. Be careful, a lot of the internet sites like to lie about the suggested price, then give you a fairly high price and tell you it is a sale. Getboards will give you the real deal. Good luck!
(oh, and if it helps, my first twins were Line Chronics and they changed my life)