I tried using my Nook Color as a PDF reader for textbooks and other technical publications. In short, it didn't work very well. For an illustration & diagram he

I tried using my Nook Color as a PDF reader for textbooks and other technical publications. In short, it didn't work very well. For an illustration & diagram heavy text, the Nook Color was too slow (the Tab 7 would probably be fine) in rendering pages, and the screen was too small to show much of a page. So I upgraded to a 10" Transformer and had a much better experience. So depends on what your PDF is like. For basic text, the 7 inch screen was fine. For technical papers, you'll probably want something bigger.