PDF viewer?

Hi all I am in my first year in uni and right now my subjects require me to print about 100 pages per week as lecture notes that I have to bring every day plus buy some extra books.

I have found out that these books are available in the uni's website in PDF format to download however I have no idea what device to get if I were to switch to PDFs instead of buying textbooks. Also do these pdf viewing devices allow you to right little notes? Don't want to buy tablet PC as it is expensive for me

 

Here is a link to free PDFZilla software http://www.pdfzilla.com/giveaway.html Registration Code listed in link: AQ1W6F0ZN7Q9D85