I use a Samsung Chromebook - the one running an ARM Processor and looks like an 11" MacBook Air but costs only £200.
I quite like the brand new Overdrive Read which displays ePub files in the web browser. Basic, but it does all I want.
http://www.overdrive.com/products/overdrive-read/
I switch the Chromebook into full screen mode which gives plenty viewing area. It is also possible to rotate the screen for a big-big-book read. Holding the ultra-portable laptop with the keyboard on the right or the left is entirely manageable. The graphics driver control panel of a Windows laptop ought to make screen orientation changes.