No Overdrive library here, but the library that I'm a member of (The Hague) has a partnership with
www.netlibrary.com and they use ePub + DRM, which will work with my PRS-700
So Europe isn't completely cut off from ebooks via libraries!
I still have to go sign up (can only do that at the library, not directly online), I wonder how big their English collection is. They mention their Dutch collection is only about 300 titles, but I read mostly in English anyway.