I am a student and I'm interested in a mobile computer purchase, but I'm not really sure what would be the best purchase.

I want something lightweight and portable (I already have a laptop, something smaller, more handheld) that I can download things onto - it will especially be journal articles, reviews, book extracts, maybe whole books.

I am basically looking for a reading tool, so that I don't have to print out lots of pages for a journal article I might read once or twice.

I would like to use it on train journies, or just around campus.

Obviously, being a student, cost is an issue. I also don't want to be bound into one format or one vendor for reading material. It has to be easy to read, hopefully in daylight too.

Any suggestions?