Instead of carrying a heap of books around with you for when your on the bus to school/work or wherever it would be far more practical having some kinda digital ebook reader. Personally I been using my NintendoDS but it can only read .txt or .html (without pictures) files unfortunately.
What would be the best device to get for reading .PDF's? One of those mini business computers would be overkill since I only wanna read PDF's and maybe look at some pictures.
You can get a used PDA (I'm guessing that's what you mean by mini business computer ) on ebay for about £30-40. It doesn't have to be very new - those from 3 or 4 years back still have colour screens and are capable of showing photos and viewing PDFs. Plus, it'll be able to do a lot more too.