It includes its own player - does not use kontakt - so there should be no interference with anything else on your computer. I have the trumpets and am very happy with them. They aren't perfect, but I find them very playable and easy to use. I'll be buying more from them as I can afford to.
I have the Horns and Trumpets, as well as the Flutes and English Horns and I am very impressed with them (you can't get them seperately anymore, now they only come in bundles if you haven't already bought some). I love the dynamic range on the brass, and I will be getting the rest of the brass hopefully by christmas. They may not replace everything you own, but I think they are well worth the cost. I do wish you could still buy individual instruments, but they are still worth it if you have the money to spend all at once.