Hi CFardon,
Unfortunately, the dll must be registered as part of the install - it runs a special script. If terminated early, the install is incomplete.
Which version of Office are you running on vista ultimate 64-bit?
Can you check if you have the file 'C:\Documents and Settings\<user name>\My Documents\Add-in Express\adxloader.log' and post it here? It will contain a detailed log indicating the problem.
Cheers,
Andrew