If you have the "Adobe Shockwave" installed, that is the current version.  Why are you trying to install some other Shockwave version?  (Adobe purchased Shockwave about two years ago).

However, Adobe has a small utility to completely remove shockwave from the PC.  I had problems installing shockwave for a client and had to run the uninstaller, restart the PC, and then I was able to install Adobe Shockwave. 

HERE is the Adobe flash uninstaller.

Adobe Flash Player has to be installed.  There are games on shockwave site that require the Flash Player.  Some require Adobe shockwave and some require Java.  I have tried both XP and Vista all with the same results.  I used both from the recovery CD from Dell and even tried a regular version of XP all with the same results.  I had all running on another system just fine just have trouble on the Dell.  Since changing to Dell system I have been unable to run any downloads from Shockwave. 

Did you do as I noted?  run the Adobe flash uninstaller restart the PC and then download and install the latest Adobe flash?  If not, try that. 

It's not a "Dell" hardware or software problem, it's some configuration issue you have or your security software is not allowing it.