Continued use of ADE 1.7.1

I find ebooks much easier to read with version 1.7.1.  (I have problems with my vision; my eyes are sensitive to light and white backgrounds.) Also, this version is much more aesthetically pleasing than 2.0. Do I have to upgrade? I keep getting the following message:

"There is a new version of Adobe Digital Editions available.Please update now.

[Update Later (Expires in 44 days)]    [Update Now]"