I very rarely use a published adventure as written. Too many times, my players will do something completely off the wall, or just ignore something that would cause the adventure to collapse before it even gets started. I've made a little list of things that I do that makes even stuff published for completely different systems usable.
1. Maps. These are always useful. I have a collection of photocopied maps in a binder that I can whip out at a moments notice.
2. NPC's. Also always usable. It's a bonus if they're written in the system I'm using.
3. Art. That cool picture of a vampire will be used somewhere.
4. General plot lines. These can provide some great inspiration, even if the particulars in the adventure wouldn't suit.
5. Little details. The room with a neat description and associated monster might get dropped into a completely different scenario, just because I like it. I've done this with a couple adventures that I've literally not used for anything else. It's kind of my "Well, at least I got this one little room out of the book" feeling.