Pasting from PDFs can be a real pain. I don't think Word 2007 has an easy fix for it. I haven't figured out how to use wildcards yet, but you can make your life a lot easier with a few Replace steps.

You want to get rid of the paragraph breaks you don't want while keeping the ones you do. The ones you want to keep are at the end of the paragraph and will include some punctuation mark, usually a period, an exclamation point, sometimes a parenthesis, or whatever. First you want to mark those with a unique descriptor like aaa. So you replace .P, or !P or "P with .aaa, or !aaa, or "aaa. These are the good ones. Then you replace all the other paragraph marks with nothing (just leave the "Replace with" box empty). Then go back and replace aaa (don't replace the period, just aaa) with ^p^p (two paragraph marks) and you're done.

Sometimes the punctuation at the end of sentences is followed by a space, so you put . P in the "Replace" box. You have to be aware of little things like that.

This isn't 100% foolproof. You'll still have to do some manual editing but compared to the alternative it's a cake walk. Or you can learn wildcards (might be easier).