I downloaded the Microsoft Visual C++ binary files and installed them according to the wiki. I also changed the project property values as instructed. Compiling the "Hello World" example works fine, but when trying to build the project, the program halts with the following pop-up:

"Unable to Locate Component - This application has failed to start because alld42.dll was not found."

I did check that I had copied the alld42.dll into the /system32 directory. My guess is that this problem has something to do with the fact that I'm running on 64bit Vista, since before I had successfully installed Allegro on an old XP machine. Thanks for any help in advance.

Thank you very much Thomas! I found the SysWOW64 directory and now everything works perfectly.