Hmmm, both the HTC Desire and the HTC Inspire have capable CPUs, lots of memory, and Android 2.2+ installed (Inspire) or available (Desire).

Do you want to try installing from Mozilla's ftp site instead of the Play store? If U.S. English isn't your preferred language, navigate up a level using the Parent Directory link to select a different one.

http://ftp.mozilla.org/pub/mozilla.org/mobile/releases/14.0.1/android/en-US/

There are many resources for how to install an APK file from an unofficial site, and this is just the first Google result. You probably should research around a bit more to become comfortable with it. Also, you might re-disable the feature after using it to avoid any accidental or unwanted installations.

Maximum PC | How to Sideload Android Apps

dont see how that helps me get firefox onto my phone as a better web browser.

I thought the problem was that the Play store was denying access to the app. If you are unable to install Firefox from the Play store, you can try installing it from Mozilla's site instead. If the program still doesn't run, that's a different problem.

that is the issue however i have never loaded an app via slideloader or just putting the apk file on the phone or on the sd card hence my issue of installing it.

I figured it out thanks for pointing me in that direction