Well, quit it.
So you're using Windows, and you need to view a PDF. Although Microsoft did think to include an XPS reader, they didn't think to include a PDF reader for some reason. So I guess you'll have to download Adobe Reader, right?
Well, hold on now. Do you have Chrome or Firefox? Well you should, and they both already do that. Plus they do other things too, like browse the internet. If you just want to display a PDF, they win over Reader for load time hands down. Plus you can have multiple documents open in tabs at the same time. There's even a Chrome plugin to convert PDF to Word documents for free. Adobe charges $20 a year for that service, but I'll admit I haven't actually tried either. Also, to be fair, there are features Adobe Reader has that Chrome and Firefox don't. The truth is, they can't even do two page reading mode.
Now before you go running back to Adobe Reader, give Foxit Reader a try. I'll warn you from the start that it appears to me to be as bloated as Adobe Reader, so I don't use it for basic displaying of PDF's. I use Chrome for that. However, if I want to do something Reader can do but Chrome can't, such as two page reading, or annotation, I reach for Foxit.
And if I want to something Reader can't do... I still reach for Foxit. Things like fill out any form. It can can even display multiple PDF's in tabs like Chrome and Firefox, and installs a virtual Print-to-PDF printer, so you can create a PDF from anything that can be printed from any program. Now you may be thinking that Adobe Reader can fill out forms too, and you'd be right. Some PDF forms can be created in a way so that they can be filled out in Adobe Reader. Foxit on the other hand, can type anywhere on any PDF.
But how will you display your Adobe Digital Editions® PDF's?
Alright, ya can't. The only way to display Adobe's proprietary DRM documents is to use their product.