Which operating system, including version, is this on?
I am on Windows 7.
You can download Flash Player 7 from this link http://fpdownload.macromedia.com/get/flashplayer/installers/archive/fp7_archive.zip
After downloading the zip file, extract it and you will see several folders for every FP 7 release. I would recommend using the last release, r73. I believe Quickbooks requires the ActiveX Control. If so you'll want to use the file flashplayer7r73_winax.exe (inside fp7_archive.zip\fp7_archive\r73). If this one doesn't work then use flashplayer7r73_win.exe (NPAPI plugin). You can ignore the other files (.hqz and .tar.gz) as they are for Mac and Linux.
This version was originally released in Dec 2007 and does not contain any security fixes since its release. As such, once you install Quickbooks 2005 you'll want to update Flash Player to the latest version to ensure you have the latest, most secure version. You can download the latest version by going to https://get.adobe.com/flashplayer. If you use multiple browsers (e.g IE and Firefox) you'll want to do this for each browser as they use different plugins (IE uses ActiveX Control and Firefox uses NPAPI plugin).