Update.

Promised I'd let you know how I got on with my Kindle.  So - pro's: there's a lot of free stuff out there, and most of the non-free stuff is significantly cheaper than the paper version.  There's a search facility which is very useful for me, because I so often come across a name in a book and think "Who the hell is that, then?", and have to spend ages flicking back trying to find it, so now all I have to do is type it in and the Kindle will highlight all the places where it's occurred.  You can adjust the text size, which is a boon when it's late at night and your eyes are getting tired - instant large print!  Cons:  it doesn't "feel" right in the hand and it doesn't do page numbers, it deals in "locations" which I don't find terribly user-friendly.  Also not all books are available in Kindle format - which can be annoying when it's something you're desperately looking for.  All in all though, glad I bought it.  It doesn't replace paper books by any means but it does provide a useful alternative.