Read Overdrive library ebooks on the original iPad (first generation iPad)

The first generation iPad cannot be upgraded to iOS 6 or better, and therefore can no longer have the Overdrive Media App installed. (Our first gen iPad is at iOS 5.1.1, and that seems to be the latest version it supports) However, Overdrive now offers a "read in browser" option that works very well, and works in Safari (the web browser installed on the iPad).
Just log into overdrive.com with your library info (card number and PIN), and when you find a book you like, choose to Read (In your Browser):

Here's the Overdrive info on this option.
More information here from a library system that has a nice set of pages on it, with various links to tips on reading in your browser, how to download a book for offline access when you go somewhere without internet access, etc.)

Note that not all books have the read in your browser option, from what I hear... but the ones I've spot-checked already all do. So good luck.