Some people have had issues using the Search option within Windows Vista to have search results show PDFs (in addition to Word docs, Excel docs, etc…). Adobe has a solution to this. You have to download and install iFilter which fixes the problem.
But before you go through the hassle, make sure you have PDFs set to be indexed and searchable in Windows Vista. Open “Control Panel.” Go to “Indexing Options.” Click the “Advanced” button and then click the tab “File Types.” Scroll down and make sure that the PDF file type is selected. If not, select it and PDFs will now be indexed and searchable. If it is checked, then you will need to download the Adobe iFilter software. Adobe iFilter Software