Skim is a PDF reader and note-taker for OS X. It is designed to help you read and annotate scientific papers in PDF, but is also great for viewing any PDF file.
Yet another reason to convert to Mac.
Vista is apparently the biggest reason.
Two people now have said almost the exact same thing to me, "I bought a new laptop, and it had Vista on it... it's awful. I wish I still had XP..."
Can Vista be that bad? Maybe not, but I know I won't be trying it any time soon...