If there was a sure way of doing that, I would have posted it in my initial
response. Unfortunately, as I stated, most applications weren't designed
for this type of multi-user environment and until app developers catch up
with the OS, you will need to install legacy applications this way. Some
current applications now offer the option of making them available to all
users or just the current users during setup but if you have a lot of
applications that are pre-XP and even many post-XP release (those released
close to the time XP was released) they don't offer this option.
You can try installing them into the "All Users" folder and this may work
with some applications but you must understand, the process is app
dependent. There are some, perhaps many applications with which this simply
won't work. The one sure way I've found when the above is not available or
does not work which is often the case is to do as I have described.